Folate, a B vitamin, is a tremendously important part of our diet. We need it to make and repair DNA, and to synthesize chemical messengers and nerve sheaths in the brain. When folate doesn’t pass from the blood into the brain as it’s supposed to, it can lead to extremely low muscle tone and serious neurological problems.

Could low folate also contribute to autism?

A handful of scientists say it’s possible, but solid evidence has been hard to come by. A new study, published 10 January in Molecular Psychiatry, claims that low folate levels are a problem in children with autism and offers a tenuous explanation for the low levels.

Many children with the disorder carry immune molecules in their blood that may block the passage of folate from the blood into the brain, the researchers found. The study lacks a control group of healthy children, however, putting many of its claims on shaky ground.

The biggest obstacle in folate studies is that researchers must analyze cerebrospinal fluid (CSF), which can be gleaned only from a spinal tap. Because this is an invasive procedure, little is known about the range of CSF folate levels in healthy people.

A couple of studies in the past few years have reported lower CSF folate levels in children with autism than in controls. At the Society for Neuroscience annual meeting in November, researchers reported that 5 of 67 children with autism had CSF folate levels below the normal cutoff of 40 nanomoles per liter.

Folate levels in the blood of these children, however, are normal, suggesting that the problem may lie in folate’s transport to the brain.

In the new study, researchers screened blood samples from 93 children with autism for immune molecules called folate receptor autoantibodies, or FRAs. Of these children, 56 carry a ‘blocking’ FRA, which interferes with the folate receptor, and 41 have a ‘binding’ FRA that binds to the receptor but doesn’t affect its function. Some of the children carry both kinds of FRAs.

Of the children who tested positive for at least one of these autoantibodies, 16 received spinal taps to collect spinal fluid. All of them had folate levels lower than the reported normal average of about 80 nanomoles per liter, but none showed levels below 40 nanomoles per liter.

The researchers did find an intriguing association: The lower the CSF folate level, the higher the concentration of blocking FRA in the blood.

To supplement a possible folate deficiency, they gave 44 of 70 FRA-positive children leucovorin, a pill that contains a form of folate called folinic acid, twice a day for a month or longer. Afterward, their parents reported improvements in verbal communication, language, attention and stereotypical behaviors, compared with parents of children who did not receive the treatment.

Because the study lacks a control group, it’s hard to know what to make of any of these numbers. Notably, none of the children who had their CSF tested had folate levels below what’s considered normal, which calls into question the very idea that folate deficiency contributes to the disorder. 

The autoantibody levels in the children in this study do seem high: Previous work by some of the same researchers — who hold a patent on the test — found these autoantibodies in just 7 percent of healthy women in Spain and in 13 percent of women in Ireland.

Still, I think it’s premature to use these data as the basis for a new treatment for autism. Because their study did not have a placebo group, there is no hard proof that leucovorin works.

Until we have better data on autoantibody levels in healthy people, the study presents interesting, but at best speculative, ideas about the role of folate in autism.

Population control: Analyzing schizophrenia-associated mutations in a large group of individuals from the U.K. corroborates some associations.

A new study uses data from more than 10,000 typical individuals to validate candidate regions implicated in schizophrenia. The results were published 5 November in Schizophrenia Research¹.

In the past few years, several studies have associated copy number variations (CNVs), which are duplications and deletions of chromosomal regions, with schizophrenia as well as autism. These analyses typically compare the frequency of CNVs in people who have the disorder and control populations.

Each CNV is present in no more than about one percent of individuals with schizophrenia, and is only two to ten times more prevalent in this group than in controls. Because of this, these studies must include large numbers of individuals to find statistically valid associations.

Large datasets that contain genomic information for relatively healthy individuals are scarce, however. As a result, most studies have analyzed a well-established Icelandic dataset, potentially limiting the findings to variants unique to that population.

In the new study, the researchers looked at the prevalence of several schizophrenia-associated CNVs in 10,259 individuals from the Wellcome Trust Case Control Consortium in the U.K., whose genotypes have not been used in previous schizophrenia studies. Individuals in this group have any one of a number of disorders, including heart disease, Crohn’s disease, rheumatoid arthritis and diabetes.

The researchers excluded individuals diagnosed with bipolar disorder because genetic variants in these individuals are known to overlap with those seen in schizophrenia.

They compared the frequency of nine CNVs associated with schizophrenia in the published literature with their prevalence in the control group, and confirmed the association with the disorder for six of these CNVs: deletion of 1q21.1, 3q29, 15q11.2, 15q13.1 and 22q11.2, and duplication of 16p11.2.

Deletions of 16p11.2 and 1q21.1 have also been associated with autism.

Associations between schizophrenia and the other three CNVs — duplication of 16p13.1, and deletion of 17p12 or 15q11.2 — do not appear to be statistically valid, according to the new data. In particular, the researchers found that the frequency of the 16p13.1 duplication in the dataset is the same as that previously reported for individuals with schizophrenia.

Looking at the associations between these CNVs and other disorders represented in the U.K. group, they found the highest rate in individuals with diabetes and the lowest in people with rheumatoid arthritis.

Studies have suggested that individuals with rheumatoid arthritis are less likely than controls to have children with schizophrenia. This may be because the same genetic variant helps protect against one disorder but increases the risk of developing the other, the researchers say.

References:

1: Grozeva D. et al. Schizophr. Res. Epub ahead of print (2011) PubMed

UC Davis-MIND Institute

Deep sleep: Only ten years ago, researchers often relied on sedation for imaging children with autism, but that is becoming increasingly rare.

Scanning children’s brains while they sleep is a viable alternative to sedation for infants and toddlers across the entire autism spectrum, according to a study published in the January issue of the Archives of General Psychiatry¹.

Even children with severe forms of the disorder can be successfully scanned during sleep, the study suggests, dispelling concerns that the technique biases studies toward higher-functioning children.

The finding is good news for autism researchers, who face mounting concern over the long-term effects of sedation even as the need for longitudinal imaging studies of young children grows.

Only ten years ago, the use of anesthetics such as propofol was standard for any imaging studies involving young children with autism or other developmental delays. But that has changed in the face of emerging evidence that these drugs may adversely affect the developing brain, prompting concern among both scientists and parents.

In response, autism researchers have developed a variety of tricks for coaxing infants and toddlers to sleep in magnetic resonance imaging (MRI) instruments. These sleep protocols now play a central role in brain imaging studies of autism.

The new study draws on data from the Autism Phenome Project at the MIND Institute of the University of California, Davis, to assess abnormal brain size in toddlers with autism. The researchers, led by Christine Wu Nordahl, assistant adjunct professor of psychiatry and behavioral sciences at the institute, analyzed changes in amygdala volume among a cohort of 45 boys with autism and 25 typically developing children.

Validating the sleep protocols in children with autism, although not the focus of the paper, was essential to the researchers’ methodology. They report that 88 percent of 3-year-old participants who attempted a sleep MRI were successful. Using the Developmental Quotient and the Autism Diagnostic Observation Schedule to measure developmental ability and autism severity, the researchers found no significant difference between the children who responded to the sleep protocols and those who did not².

Serious concerns:

Researchers’ interest in early brain development overlaps with growing concern about the effects of anesthesia in young children. Animal studies have linked general anesthesia in rat pups with neuronal cell death and long-term effects on memory and learning. The most significant side effects occur in pups that were anesthetized during the period when the brain is forming many new connections between neurons. In humans, this process peaks between infancy and 3 years of age³.

The rat studies are alarming, but their implications for people are unclear. The researchers gave the rats cocktails of anesthetics at doses much higher than would typically be given in the clinic. Studies of children who had surgery in infancy have so far not found a causal link between anesthesia and long-term effects. For instance, children with multiple anesthesia exposures appear to be at a higher risk of learning disabilities, but it is unclear whether this is the result of the anesthesia or of the underlying illness that required the surgery⁴.

Still, all these suggestive findings have caused concern among scientists, not to mention generated much media coverage. Several studies are underway to develop a stronger evidence base, including Smart Tots, a national research initiative funded in part by the U.S. Food and Drug Administration.

In the meantime, the ability to use sleep instead of anesthesia makes research studies more attractive to parents of young children.

“I wouldn’t have been involved if they had to sedate my boys — not that many times,” says Shamay Bartlett of Citrus Heights, California. Bartlett’s eldest son was scanned twice for the Autism Phenome Project and her 2-year-old twins were scanned three times each for a different study at the institute.

The Infant Brain Imaging Study, a multi-site project that requires 500 infant siblings of children with autism to be scanned at 6, 12 and 24 months, relies almost exclusively on sleep scans. Launched in 2008, it is funded in part by the Simons Foundation, SFARI.org’s parent organization.

“We always insist on trying natural sleep first,” says Stephen Dager, professor of radiology at the University of Washington, one of the study sites. Dager says although sedation is an option for the 24-month-olds, who tend to resist sleep more than infants do, none at his site have needed it so far.

Successful sleep scans require plenty of patience, flexibility and collaboration with parents.

“It’s not rocket science,” says Nordahl, who developed a sleep imaging protocol as part of her post-doctoral fellowship at the MIND Institute. The institute conducts a variety of brain imaging studies on young children, including the Autism Phenome Project, which uses various measures of development, including MRI scans, beginning when children are 2 to 3.5 years of age.

Sleep strategy:

In a 2008 paper, Nordahl and her colleagues reported a 93 percent success rate in obtaining bedtime MRIs from children with autism and typically developing children aged 2.5 to 4.5 years. In contrast, a paper three years earlier reported that less than half of scans obtained during sleep were usable⁵.

But researchers cannot take anesthesia out of their toolbox yet. Sleep protocols appear to lose effectiveness in children older than 5 years, especially those on the lower-functioning end of the autism spectrum. MRI studies in older children and teenagers continue to rely on sedation.

“I think everyone in the community would prefer not to do it. There is an element of risk, known and unknown,” says Heather Hazlett, assistant professor of psychology at the University of North Carolina School of Medicine. However, she notes that one-time anesthesia is generally regarded as safe, and without it researchers would not have access to data about brain development in older children with autism.

The emphasis on imaging during natural sleep in the research community stands in contrast to clinical medicine. In the U.S., some six million children are given anesthesia every year, and sedation is standard for young children in hospital MRI labs.

Peggy Seidman, associate professor of anesthesia at Stony Brook University School of Medicine in New York, says many doctors opt for scans when making an initial diagnosis in lieu of a careful physical and patient history. “We are ordering a lot of scans on kids that we didn’t before.”

Whether the sleep protocols have a larger impact on medical practice remains to be seen. Hazlett says clinical MRI labs lack basic features that make sleep scans successful, such as the ability to dim the lights. “When we go to the hospital and tell them we can scan a 12-month-old without sedation,” she says, “they look at us like we’re crazy.”

This article has been modified from the original. The previous version incorrectly stated that Shamay Bartlett's 2-year-old twins participated in the Infant Brain Imaging Study.

References:

1: Nordahl C.W. et al. Arch. Gen. Psychiatry 69, 53-61 (2012) PubMed

2: Amundsen L.B. et al. J. Neurosurg. Anesthesiol. 4, 180-192 (2005) PubMed

3: Sun L. Br. J. Anaesth. 105, i61–i68 (2010) PubMed

4: DiMaggio C. et al Ped. Neurosci. 13, 1143-1151 (2011) PubMed

 5: Nordahl C.W. et al. J. Autism Dev. Disord. 38, 1581-1590 (2008) PubMed

Functional fragments: The levels of microRNAs vary between neurons that activate brain signals and those that inhibit them.

Researchers have mapped the levels of tiny RNA fragments that regulate gene expression in specific brain regions and subtypes of neurons. The results were published 12 January in Neuron¹.  

MicroRNAs, or miRNAs, turn genes on and off by interfering with the messages that code for proteins. Studies have found abnormal levels of the molecules in postmortem brains from individuals with schizophrenia and those with autism.

The precise role of miRNAs in the brain remains unclear, however. This is partly because traditional methods of detecting and measuring miRNAs require researchers to grind up brain tissue, preventing a fine-tuned analysis of miRNA expression across subtypes of neurons.

Techniques used to separate different kinds of cells — such as sorting them by using fluorescent markers — have been another limitation. They are labor-intensive and can cause cell damage, which may lead to changes in gene expression, the researchers say.

To overcome these limitations, the new study uses a two-step approach to carefully isolate miRNAs from subpopulations of cells, such as certain types of neurons. First, the researchers tag AGO2, a protein that binds to both miRNAs and their targets in intact cells, and then they use antibodies against this tag to extract the miRNAs.

The second step takes advantage of a protein called Cre that can toggle gene expression on and off in specific cells and at specific stages in development. Using Cre, the researchers can restrict the AGO2 tag to specific subsets of neurons or brain regions. For example, they can limit expression to parvalbumin-containing cells, which are a subset of inhibitory neurons.

Using this method to study mouse brains, the researchers found that nearly 500 miRNAs are expressed differently in excitatory neurons and subtypes of inhibitory neurons. The researchers also identified 23 novel miRNAs.

The approach can be used to identify miRNA expression patterns in specific inhibitory or excitatory neuronal circuits, the researchers say. These expression differences could contribute to changes to neuronal circuits that have been described in individuals with autism.

References:

1: He M. et al. Neuron 73, 35-48 (2012) PubMed

Double duty: The antidepressant Prozac has no effect on children with autism, but seems to improve repetitive behaviors in adults with the disorder.

Fluoxetine, an antidepressant marketed as Prozac, may alleviate repetitive behaviors in adults with autism, according to a study published 2 December in the American Journal of Psychiatry¹.

The results are in contrast to several studies showing that antidepressants, including fluoxetine, have no effect on repetitive behaviors in children with the disorder.

Repetitive behaviors and restricted interests, a core feature of autism, share some overlap with obsessive-compulsive disorder, which is often treated with selective serotonin reuptake inhibitors, or SSRIs, such as fluoxetine. Because of this, a number of studies have investigated whether SSRIs could also help individuals with autism.

The results have been inconsistent and generally negative. A 2009 study found that the SSRI citalopram is no better than placebo at alleviating repetitive behaviors in children with autism². A clinical trial that same year also found that fluoxetine has no effect on repetitive behaviors in children with the disorder.

However, the only study to look at the effects of fluoxetine on adults with autism, according to the researchers, showed improvements in repetitive behaviors³.

The neurotransmitter serotonin, which regulates mood, appetite and sleep, has been linked to autism. Children with the disorder have been shown to have high levels of serotonin in the blood and lower-than-normal brain activity of a protein that regulates serotonin levels.

In the new study, researchers looked at the effect of fluoxetine, which has broader and longer-lasting effects than does citalopram, in 37 adults with autism. Of these, 22 were treated with fluoxetine for 12 weeks and 15 received a placebo. Neither the participants nor the researchers knew who was receiving which dose.

The researchers used the Yale-Brown Obsessive-Compulsive Scale and the Clinical Global Impression (CGI) scale to assess repetitive behaviors in participants. They also used the latter scale to measure overall functioning. 

Adults with autism who received fluoxetine showed greater improvements in repetitive behaviors compared with those who received the placebo, the study found. For example, using the CGI scale, 35 percent of individuals on the drug showed global improvements, compared with none of controls, and 50 percent showed improvements on repetitive behaviors, compared with 8 percent of controls.

The side effects of the medication were mild, the study found.

The discrepancy with previous findings may be due to differences in the effects of fluoxetine compared with citalopram and in the way it functions in adults compared with children, the researchers say. They recommend further research into the effects of the drug on different forms of repetitive behavior, such as obsessions, rituals and routines, and stereotyped movements.

References:

1: Hollander E. et al. Am. J. Psychiatry Epub ahead of print (2011) PubMed

2: King B.H. et al. Arch. Gen. Psychiatry 66, 583-590 (2009) PubMed

3: McDougle C.J. et al. Arch. Gen. Psychiatry 53, 1001-1008 (1996) PubMed

For the past few years, genome-wide association studies (GWAS) have been the favorite whipping post among some geneticists.

The approach is used to identify common variants that predispose individuals to particular complex traits or diseases, but critics have argued that it is too expensive, identifies variants of little predictive value or impact in the clinic and, overall, has been subject to a great deal of hype.

The latter charge has been particularly difficult to rebut: A piece in Newsweek referred to 2007, the year that inaugurated the GWAS era, as an annus mirabilis, or miracle year — a label that had been assigned only to 1905 and Einstein’s revolution in physics.

Let’s agree that was an overstatement.

Still, I count myself among those who think the approach has been successful and feel that there is no reason for proponents of GWAS to feel defensive about their achievements. Three recently published overviews of GWAS-based discovery explain why.

Though technically challenging, a GWAS is conceptually simple: Researchers scan about one million common single-nucleotide changes in the genome to see which ones occur more frequently in individuals with particular diseases compared with healthy controls.

The first review, published this month in The American Journal of Human Genetics, provides an overview of the more than 2,000 genetic loci that have been robustly associated with complex traits in humans, and shows that their identification has generated important new leads into the causes of human disease.

In at least some cases, particularly for autoimmune and metabolic disorders, these leads may be clinically relevant in the near future.

A common criticism of GWAS is that variants individually confer a small amount of disease risk, and that collectively they explain only a fraction of the overall heritability of a disease or trait.

But the researchers point out that for some disorders, common variants identified by GWAS already account for close to 20 percent of the genetic variance in risk. This fraction only seems small if one ignores the fact that five years ago the value would have been close to zero for most diseases.

What’s more, the researchers say, the main goal of GWAS has always been to use genetics to provide insights into the underlying biology of disease. This has clearly been attained.

What are the prospects for GWAS of autism spectrum disorders? The second paper, published last May in Schizophrenia Bulletin, points out that success is all about sample size, and that it’s possible to predict the numbers needed to generate robust associations between variants and disease traits.

GWAS studies on autism have thus far been too small, so only a couple of variants have emerged that look promising, and each of these awaits independent replication. 

Based on what we know about schizophrenia and other complex diseases, sample sizes of 10,000 to 20,000 people would be very likely to yield multiple new associations in autism. Recruitment through the Interactive Autism Network, an online registry of individuals on the autism spectrum, could be one way to reach this goal.

Finally, I recommend a third paper published this month in Nature Reviews Genetics, which points out what should be obvious by now: Rare and common variants both have substantial roles in conferring disease risk. In fact, the paper offers a model that integrates the entire spectrum of variants an individual carries into an explanation of disease susceptibility.

The challenge of the next few years will be to rigorously test this model based on the collective effects of known risk variants — whatever their frequency.

Stumpy spines: PSD-95 (green), a protein that sits at the tip of the spines that receive neuronal signals (top), is mislocalized in neurons that lack neurobeachin (above). 

Neurobeachin, or NBEA, an autism–associated gene, may regulate the transport of signaling molecules to neuronal branches, according to a study published 22 November in Nature Communications¹.

The study hones in on a possible mechanism by which an autism-associated mutation disrupts the function of synapses, the junctions between neurons.

Synapses are far removed from the cell body of a neuron, so their function depends on the transport of a cocktail of molecules along neuronal projections. This mix of molecules regulates synaptic plasticity — changes in the strength of the connections between neurons — defects in which have been implicated in autism. 

In the new study, researchers investigated the effect of NBEA on synapses by looking at cultured neurons from mice lacking both copies of the gene. Because these mice die shortly after birth, they also studied brain tissue from adult mice with one copy of NBEA.

Actin, which mediates transport in a cell, accumulates in the cell body instead of at synapses in the mutant neurons, the study found. In addition, synaptopodin, a protein that is usually found at synapses, is localized predominantly in the cell body and overlaps with actin. These changes suggest that in normal cells, NBEA plays a role in the transport of molecules to the tips of neurons, the researchers say.

The researchers also saw defects in dendritic spines, the mushroom-shaped bodies that generally receive excitatory impulses from other neurons, compared with controls. Immature or malformed dendritic spines are a feature of both autism and the related fragile X syndrome.

Neurons from mice lacking NBEA have fewer dendritic spines than controls do, the study found. The shape of the spines is also different: They lack the typical mushroom-shaped head, and so instead form connections with other neurons on their shafts.

The researchers also looked at two proteins that serve as markers of neurons that transmit excitatory and inhibitory signals in the brain: PSD-95 and gephyrin, respectively. An imbalance between excitatory and inhibitory neurons is one theory that has been suggested to explain the deficits that lead to autism. 

The researchers found that PSD-95, the excitatory molecule, is mislocalized to spine shafts in mutant cells. It is also more abundant in mutant neurons than in controls. By contrast, the localization and amount of the inhibitory molecule, gephyrin, is unaffected, the study found. Neurons lacking NBEA also make more connections with excitatory neurons than do controls.

The neurons in NBEA-deficient mice could be compensating for the changes to dendritic spines by increasing the number of excitatory synapses between cells, the researchers say.

References:

1: Niesmann K. et al. Nat. Commun. 2, 557 (2011) PubMed

Facing forward: When Tony Charman first began studying autism in the 1980s, long-term studies of individuals with autism were rare.

The first person I encountered with autism was during my clinical training in the 1980s. She was a young woman with mild intellectual disability whose erratic behavior had led her to be in a secure psychiatric hospital setting. Getting to the root of her conduct entailed, among other things, meeting her parents and taking a full developmental history.

This allowed us to understand her adult behavior in the context of how she was as a toddler, a child and an adolescent. It became clear that for this individual, the characteristics of autism had emerged early in her development, probably in the 1960s, at a time when they were not necessarily understood.

These days, things are different, and clinicians and autism researchers are more aware of the early signs of autism and the need to take into account an individual’s developmental trajectory, which is essential for understanding the disorder.

The first major collaborative research study that I was involved in was the Checklist for Autism in Toddlers, or CHAT, population screening study¹. In this study, we attempted, for the first time, to prospectively identify autism at the age of 18 months by administering a checklist and a brief assessment to 16,000 toddlers. We then followed up with a tiny proportion of these children at 20 months and again at 42 months of age.

It was a challenge to decide what to measure and what to expect in typical and possibly atypical toddlers. The experience also made me realize that to get the most out of a large study in which so many infants were being screened, we had to follow the children over time. Our team was privileged to see some of the same children for the fourth time at 16 years of age², and this past December we secured funding to see them again as young adults.

Developmental disorder:

In some ways it is obvious that long-term studies are required to understand a developmental condition such as autism. However, in 1990, when we began the CHAT study, cross-sectional studies were the norm and longitudinal studies were rare, with some exceptions³.

There are many reasons why this was the case. They range from the pragmatic — longitudinal studies are expensive, difficult to fund and are a slow way of building your curriculum vitae as a researcher — to the scientific.

The field was still getting to grips with what autism is, let alone how it develops. What has been remarkable in the 20 years since is how seriously the field has taken on the challenge of understanding autism as a developmental disorder.

There are now many examples of longitudinal studies in a number of different areas of research, ranging from diagnostic and outcome studies to studies of cognition, neuroimaging and, very soon, genetics.

In the clinical realm, studies by Catherine Lord and her colleagues have found that an autism diagnosis, in particular for idiopathic autism, is highly stable from 2 years of age to mid-childhood, about 9 years⁴.

Peter Szatmari and his colleagues looked at how autism symptoms changed in children of average intellectual ability with a diagnosis of autism or Asperger syndrome between 4 to 6 years of age and adolescence. They found evidence for similar trajectories in the two groups, consistent with the notion that autism and Asperger syndrome fall on the same spectrum, and differ only in their start and end-state levels of intellectual and communication abilities⁵.

In the area of cognitive research, Liz Pellicano has conducted some of the first studies to look at how cognitive abilities, such as theory of mind — the ability to understand the beliefs of others — and executive function, relate to each other across time⁶.

These studies may reveal the developmental processes that underlie these types of cognitive processing and suggest how interventions can support and facilitate their development.

In the field of neuroimaging, Joe Piven’s group has demonstrated that although amygdala volume is greater in children with autism compared with controls at both 2 and 4 years of age, there is no relative increase in volume over time⁷. However, early amygdala volume is associated with joint attention skills later in development, suggesting that the amygdala plays a role in later social communication development.

At risk:

Over the past decade, many groups worldwide have also exploited a within-family recurrence of autism to study the ‘at-risk’ younger siblings of a child with a diagnosis of autism, starting in infancy.

These studies suggest that there are a number of identifiable differences that mark those siblings who will go on to have a diagnosis of autism. These are mostly in early social communication behaviors, such as their response to hearing their name, social smiling and affect.

However, perhaps to the surprise of the researchers who set up such studies, most differences have only emerged around the infant siblings’ first birthday and into the second year of life. Very few, if any, studies so far have found clear predictors as early as 6 months of age⁸.

At-risk sibling studies have provided other surprises. Sally Ozonoff and her colleagues have found that three-quarters of the high-risk group who go on to have a diagnosis of autism show a plateau or decline in early social communication skills after their first birthday, but are indistinguishable from low-risk controls at 6 months of age⁹.

A report by the same group, published in 2009, illustrates another unexpected finding¹⁰. With 6-month-old high-risk infants, the researchers used the classic ‘still face’ paradigm, in which a mother provokes a distress response from her child by freezing her expression during play. They used a combination of behavioral and eye-tracking measures to identify the infants’ response, which included gaze aversion, negative affect and lack of social smiling.

However, the infants’ reaction to these still faces does not predict a diagnosis of autism at 24 months of age — their looking and smiling behavior shows the usual distress response to the change in their mothers’ interactive behavior.

Many of us would have predicted that disruptions in the infant-caregiver interactive communication would identify high-risk infants who would go on to be diagnosed with autism. But to date, this has not been the case.

Along with many other clinicians and researchers whose interest has traditionally been young children with autism, I have become increasingly interested in understanding the challenges faced by adults on the autism spectrum.

In part, this is because the infants and children we saw two decades ago in research studies are now young adults. In the U.K., increased interest in autism in adulthood has been reflected in the policy field by the passage, in 2009, of the Autism Act, the first disability-specific Act of Parliament by the U.K. government, resulting in a national adult autism strategy.

So, compared with 20 years ago, autism research has embraced development. This is to be welcomed and holds much promise for better understanding a developmental condition, the outcome of which is due both to intrinsic and extrinsic factors.

There is great focus on the challenges that a developmental approach to understanding autism brings. Three notable areas of activity in the field are understanding developmental trajectories and their influences¹¹, developing analytic methods that allow us to model trajectories, and intervention trials to test theories about the effects of treatments¹².

My hope for the coming decade is that developmental studies of autism truly come of age to offer new insights into, and hope for, individuals with autism.

Tony Charman is chair of autism education at the Centre for Research in Autism and Education, Institute of Education, London.

References:

1: Baird G. et al. J. Am. Academ. Child Adolesc. Psychiatry 39, 694-702 (2000) PubMed

2: Charman T. et al. Brain Res. 1380, 10-21 (2011) PubMed

3: Rutter M. and L. Bartak J. Child Psychol. Psychiatry 14, 241-270 (1973) PubMed

4: Lord C. et al. Arch. Gen. Psychiatry 63, 694-701 (2006) PubMed

5: Szatmari P. et al. J. Child Psychol. Psychiatry 50, 1459-1467 (2009) PubMed

6: Pellicano E. Child Dev. 81, 1400-1416 (2010) PubMed

7: Mosconi M.W. et al. Arch. Gen. Psychiatry 66, 509-516 (2009) PubMed

8: Yirmiya N. and T. Charman J. Child Psychol. Psychiatry 51, 432-458 (2010) PubMed

9: Ozonoff S. et al. J. Am. Academ. Child Adolesc. Psychiatry 49, 256-266 (2010) PubMed

10: Young G.S. et al. Dev. Sci. 12, 798-814 (2009) PubMed

11: Elsabbagh M. and M.H. Johnson Trends Cog. Sci. 14, 81-87 (2010) PubMed

12: Charman T. J. Child Psychol. Psychiatry 52, 22-23 (2011) PubMed

Brain maps: Mathematical analyses of brain imaging data trace the links between highly connected nodes (thick lines) and from those nodes to other brain regions (thin lines).

Using new approaches to analyze brain imaging data, researchers have developed a way to map structural networks that are central to the flow and integration of information across the whole brain.

The way these networks are organized may reveal critical information hubs within the networks, as well as their overall efficiency — how quickly information flows from one area of the brain to another — two factors that may play a role in neurological and psychiatric diseases.

The researchers plan to apply the approach to brain imaging data from children with autism and other neurodevelopmental disorders.

This gestalt approach is made possible by rapidly expanding computing power and analytical tools borrowed from the maturing field of network science, first developed in the physical and social sciences to understand the relationships between different entities, such as people and organizations.

“We are experiencing a true paradigm shift in cognitive neuroscience in thinking about the brain in network terms,” says Bradley Schlaggar, associate professor of developmental neurobiology at the Washington University School of Medicine in St. Louis. “Neuroscientists are coopting methods developed elsewhere, and now, because of surging interest [in network analysis], are beginning to contribute to the push forward.”

Research suggests that abnormal connectivity may play an important role in autism and other disorders, by altering the transmission of information within the brain.

“We believe that many, perhaps all, neurodevelopmental disorders are related to abnormal wiring,” says Martijn van den Heuvel, assistant professor of psychiatry at the University Medical Centre Utrecht in the Netherlands, who is planning the autism study. “It could be over-connectivity or under-connectivity, or a different topology of connections.” Van den Heuvel and collaborator Olaf Sporns, professor of psychological and brain sciences at Indiana University in Bloomington, are among the first to apply these analysis techniques to brain imaging.

The whole brain:

To create the network, researchers first map out the structural connections in the brain using data from diffusion tensor imaging, an indirect measure of the brain’s white matter. Similar maps can be constructed using functional magnetic resonance imaging, which detects brain regions that are synchronously active and therefore likely to be part of the same circuit. 

Researchers then examine the network’s higher-order characteristics, such as the way its constituent parts are arranged, using mathematical tools — most notably graph theory, which analyzes the relationship between different points or objects. In this case, those objects are nodes of connectivity in the brain.

The end result is a comprehensive map of the brain’s neuronal connections, which the researchers can then pare down to examine the most highly interlinked networks.

Traditional brain imaging studies have focused on specific circuits or brain regions involved in specific tasks, but van den Heuvel’s work is part of a growing trend to analyze the function of the brain as a whole.

“Brain function, and in the case of autism and schizophrenia, brain dysfunction, does not emerge from single regions or connections,” says van den Heuvel. “It emerges from continual brain communication, which is why this is such a powerful technique to look at neurodevelopmental disorders.”

In 2010, van den Heuvel used his approach to show that people with schizophrenia may not be able to integrate information as efficiently across brain regions as controls do¹.

A subsequent study of 21 healthy adults, published in the Journal of Neuroscience last November², built on this network analysis to show that highly connected nodes in the brain are also preferentially connected to one another. The researchers suggest that this 'core' network integrates higher-order information from all other regions of the brain. 

Van den Heuvel likens this network to a “G8 of the brain.”

“The world leaders of the biggest countries have different backgrounds, but they come together to discuss topics that concern the well-being of the entire world,” he says. “Perhaps [this network] has a similar function.”  

Studying the brain’s organization in this way could also reveal how its connections change over time, during childhood and in neurodevelopmental disorders, he says.

“We know the brain is not static, especially in developing from child to adult,” he says. “Does this involve changes in the topology of the network?”

An unusual map:

Studies suggest that children with autism may have a number of subtle abnormalities in the brain’s connectivity, including weaker connections in some areas and an excess of short-range connections, bolstering the so-called connectivity theory of autism.

Van den Heuvel and his colleagues are planning to use their network approach to look for different types of connectivity deficits in children with autism.

For example, it might reveal excessive connections among specific sub-networks, or perhaps less efficient networks overall.

“From the perspective of a clinician, I’m very excited about the notion of being able to extract information from brain images that on the surface seem to be typical, but when analyzed appropriately, may reveal the basis of autism, attention deficit and hyperactivity disorder, and other disorders,” says Schlaggar, who studies connectivity patterns in children with developmental disorders, but is not involved with this work.

Identifying specific characteristics in brain connectivity might also help to link genetic mutations to different symptoms or cognitive functions.

“The topology of the brain may provide a clearer phenotype and form a bridge between genetics and brain imaging,” says van den Heuvel.

Despite its promise, network analysis of brain imaging is in the early days. Researchers are still experimenting with a number of analysis techniques and exploring both their advantages and limitations.

“It remains to be seen which network approach is going to be most useful, whether it’s from structural imaging, functional imaging or a combination,” says Schlaggar.

Indeed, findings published in the past few months show that connectivity analysis, particularly among children and those with certain disorders, requires particular care.

For example, the finding that children with autism have an excess of short-range connections may be the result of experimental artifacts.

What’s more, the imaging methods used to create the maps are indirect measures of connectivity, and it’s still not clear what exactly the networks identified in these studies correspond to in the physical brain.

“The question of what the neuronal fiber pathways of the human brain are at a large scale is not yet well-understood, either at the scientific level or at the practical level,” says Van Wedeen, associate professor of radiology at Harvard Medical School, who was not involved in the current work. “[The network analysis] approach is an exciting and promising bid for doing that, but with caveats.”

References:

1. van den Heuvel M.P. et al J. Neurosci. 30, 15915-15926 (2010) PubMed

2. van den Heuvel M.P. and O. Sporns J. Neurosci. 31, 15775-15786 (2011) PubMed

'Behavioral intervention' is one of those broad terms that I suspect many people recognize but don’t really understand. I'm one of them.

The high-level definition: It's a common and time-intensive treatment for autism, often based on applied behavioral analysis, an approach in which bad behaviors are discouraged and positive behaviors reinforced.

But it's not that simple. Behavioral interventions take many forms — discrete trial training, pivotal response training and the Picture Exchange Communication System, to name just a few. The differences among these are subtle and not easy to describe.

Happily, a new online resource of definitions and short video clips helps distinguish them.

Earlier this month, the autism science and advocacy organization Autism Speaks, along with nonprofit First Signs and Florida State University, launched the treatment section of a resource called the ASD Video Glossary. The new section compiles more than 100 video clips showing 22 kinds of treatments for the disorder.

The clips help distinguish among different kinds of behavioral intervention — just about the only thing proven to improve some symptoms of autism.

For example, in an approach called discrete trial training, the therapist rewards a child for imitating an action, such as raising his or her arms straight up. Pivotal response training, by contrast, is more natural: The child initiates what to do or play with, and the therapist directs imitation and sharing tasks from there.

The resource isn't limited to behavioral interventions. It also has videos of art and music therapy, reciprocal conversations and sensory integration therapy — in which, for example, a child learns to walk on a balance beam and play hopscotch.

This has obvious practical use for parents and clinicians who are trying to choose the therapies that would be best for a particular child. But it has a broader message, too.

The exercises are extremely repetitive and require daily practice, and the child's progress is typically slow. After watching even a few minutes of these videos, the challenges in applying these autism therapies — each and every one of them — are immediately apparent.

Toddlers with autism do not anticipate emotional moments in videos of social scenes, unlike controls, according to a study published 27 December in the Proceedings of the National Academy of Sciences. The study uses the rate of blinking as a measure of the children’s interest in the video content¹.

A 2002 study first used eye-tracking technology to compare the gaze of individuals with autism with that of controls². This technology has since been used in many studies to determine which parts of a scene people pay attention to.

Where someone chooses to look is only an indirect measure of how interested they are in the content of a scene, however, so researchers have been seeking additional ways to assess this.

At the 2010 International Meeting for Autism Research, researchers presented preliminary data showing that people blink less frequently when they look at something they find interesting.

In the new study, the same researchers expand on these findings by looking at the gaze and blink rate of 41 toddlers with autism and 52 typically developing children who watched a short video.

In the clip, two toddlers fight over whether the door of a toy car should be open or closed. Ten independent adults also viewed the video and classified the scenes in terms of their emotional content. They identified eight highly emotional scenes, such as when the toddlers seemed to be angry. The researchers also ranked the moments when the toddlers opened or shut the car door as conveying the most physical information.

Toddlers with autism and typically developing children blinked less frequently while watching the video compared with blank interval screens, the study found. Both groups also blinked most often during moments that were not classified as important. These findings support the theory that people slow down their blink rate when they are looking at something they find engaging.

But toddlers with autism have different reactions to the content of the videos than controls do, the study found. Toddlers with autism blinked more during the emotional scenes than during the physical scenes, whereas typical children showed the opposite preference. This finding supports previous data showing that individuals with autism are less attuned to social information in images or videos, the researchers say.

They also looked at the average change in the blink rate at specific times before and after the highly emotional scenes. On average, typical toddlers blinked the least 66 milliseconds before the emotional moments, whereas the children with autism blinked the least 599 milliseconds afterward. This may be because the typical children are anticipating an emotional response using subtle cues, such as when a frown precedes a scream, the researchers say.

References:

1: Shultz S. et al. Proc. Natl. Acad. Sci. USA 108, 21270-21275 (2011) PubMed

2: Pelphrey K.A. et al. J. Autism Dev. Disord. 32, 249-261 (2002) PubMed

Daddy’s girl: Girls with autism who have older fathers hint at the potential role of new mutations in the disorder.

Children with autism who have older fathers — with an average age of 41 — are more likely than those with younger fathers to be the only child with autism in their family, according to a new study¹. The finding is especially striking for girls with older fathers, who are more than six times as likely as those with younger fathers to show this effect.

The results, published online 16 December in Autism, bolster the hypothesis that de novo, or non-inherited, mutations that accumulate in a man’s sperm cells as he ages may increase the risk of autism in his children.

“It suggests that girls with autism whose fathers are older are especially likely to have a disorder that is owing to some de novo event,” says lead investigator Jeremy Silverman, professor of psychiatry at Mount Sinai School of Medicine in New York.

The findings emphasize the importance of including girls in studies of the disorder, even though they are less likely to be affected than boys are.

“This is refocusing the attention on the females, and putting forth a potential model that makes a lot of sense,” says Rita Cantor, professor of human genetics at the University of California, Los Angeles, who was not involved in the work.

About four times more boys than girls have autism. However, this skewed sex ratio narrows among children with older fathers², suggesting that some mechanism that affects boys and girls more equally may be at play in this group.

What’s more, researchers have found that people with sporadic autism — those who don’t have a family history of the disorder — have more de novo copy number variations (CNVs) than people with autism that runs in families or healthy individuals³. CNVs are a type of mutation in which chunks of genetic material are duplicated or deleted.

“There had been hints at this [study’s findings] in different ways,” Silverman says. “In some ways, we were just trying to put this stuff together.”

Separating simplex:

In the new study, Silverman and his colleagues analyzed data on 677 children with autism from 340 families enrolled in autism studies at Mount Sinai. “[Recruitment] took place before we were interested in paternal or maternal ages,” Silverman notes, “and so we feel pretty confident that there was no inherent bias” toward older parents.

Of these families, 90 are simplex families, meaning they have one child with autism, but unaffected parents and siblings. The remainder are multiplex families, in which at least two children are affected by the disorder.

The researchers divided the children into four groups based on the age of their fathers. They found that children with autism who have the oldest fathers, with an average age of 41 when their children were born, are more likely to be part of simplex families compared with those born to the youngest fathers, with an average age of 27.5 years.

As grouped, the youngest fathers of girls with autism were between 22 and 30 years old, and the youngest fathers of boys were between 20 and 29. The oldest fathers of girls were between 38 and 52, and the oldest fathers of boys between 37 and 62. But, notes Silverman, “the results could not be attributed to a few outliers — that is, to a few fathers with especially high ages.”

To the researchers’ surprise, though, the link between older paternal age and simplex families is much more pronounced in girls. Boys in the study who have the oldest fathers are one-and-a-half times as likely to be from a simplex family compared with boys who have the youngest fathers. By contrast, girls with autism and the oldest fathers are over six times more likely to belong to a simplex family compared with girls who have the youngest fathers. 

“Simplex girls are really driving that relationship,” Silverman says.

That’s consistent with the idea that new mutations can accumulate in the sperm of men as they age, increasing the risk of autism in their daughters, even when there’s no family history of the disorder.

The findings don’t preclude de novo mutations from also contributing to autism in boys. A link between paternal age and simplex autism may simply be harder to pick up in boys because there are more boys with the disorder, and a greater diversity of causative factors, Silverman suggests.

Common characteristics:

The study is small and must be validated in a larger sample, experts caution. “They only have 14 [girls with simplex autism] that establish this, which in the statistical world is quite small,” Cantor says.

Experts also note that while the results support a role for de novo mutations, they don’t rule out other possibilities. “Other things happen as men age, and those could be explanatory for their findings,” says Lisa Croen, director of the Autism Research Program at the health insurer Kaiser Permanente Northern California in Oakland, California, who was not involved in the study.

Other age-related factors could include environmental exposures or epigenetic changes, which affect gene expression without altering the underlying sequence.

Data from some large studies that collect genetic material and information on environmental exposures, such as the ongoing Study to Explore Early Development, could help confirm the new results, notes Croen.

Silverman plans to investigate whether there are other characteristics common to girls with simplex autism who have older fathers, such as the pattern or severity of their symptoms.

Last year, researchers led by Dolores Malaspina found that women with schizophrenia who have older fathers and no family history of the disease have more severe symptoms compared with other women who have schizophrenia⁴. The risk of schizophrenia, like that of autism, is greater in males and in children of older men.

Silverman says his team’s findings help point autism researchers toward the subpopulations that may be most useful for their studies. For example, those wanting to understand the role of de novo mutations in autism might want to focus on simplex girls with older fathers. Those interested in how autism susceptibility is transmitted down the generations might want to avoid that population.

References:

1: Puleo C.M. et al. Autism (2011) (Epub ahead of print) PubMed

2: Anello A. et al. J. Autism Dev. Disord. 39, 1487-1492 (2009) PubMed

3: Sebat J. et al. Science 316, 445-449 (2007) PubMed

 4: Rosenfield P.J. et al. Schizophr. Res. 116, 191-195 (2010) PubMed

Ranked resource: AutismKB lists studies that associate candidate genes with autism and rates them on the strength of the evidence.

A new online database provides searchable information for nearly 10,000 genes, variants and chromosomal regions linked to autism. Researchers describe the resource, dubbed AutismKB, in the January issue of Nucleic Acids Research¹.

Over the past few years, numerous mutations and genetic variants have been linked to autism. Most cases of autism probably result from carrying a combination of these variants.  

According to the researchers, there are three existing databases, including SFARIGene — funded by the Simons Foundation, SFARI.org's parent organization — that summarize and rank the evidence linking various genes to autism.

The new database includes autism candidate genes from a wider range of studies than do the other resources, the researchers say.

They searched the abstracts of more than 4,000 articles and identified 11 genome-wide association studies, 242 association studies that focus on candidate genes, 13 studies of gene expression, 95 studies of copy number variants — duplications or deletions of DNA — 23 genome-wide analyses that associate variants across a chromosomal region and 236 studies that link a particular gene or protein to autism.

They also searched the Online Mendelian Inheritance in Man, or OMIM, database for autism-related disorders such as fragile X and Rett syndromes. 

The researchers ranked the genes from these studies by assigning a number to each based on the strength of the evidence.

For example, for diseases associated with autism symptoms in a single individual, genes receive a score of one, whereas for diseases that show autism symptoms in multiple individuals and studies, they receive a score of four. The researchers then added up the scores for each study that links a gene to autism. 

The resource is a comprehensive overview of the literature, but may be too inclusive, some experts caution. For example, it includes genome-wide association studies with few participants, which many researchers argue are often statistically weak. 

However, users of the database can manually rank what they perceive to be the significance of various approaches. For example, they can assign a score of one to low-scale association studies.

The database also includes functional information about each gene, collected from various sources, such as the Allen Brain Atlas and the Mouse Genome Informatics resource. The functional pathways most highly associated with autism are those that involve synapses, the junctions between neurons, the study found.

AutismKB also includes clinical information from each study. For example, it lists participants’ ancestral background, age and whether their autism was diagnosed using the Autism Diagnostic Observation Schedule or the Autism Diagnostic Interview-Revised, two widely used diagnostic tests.

References:

1: Xu L.M. et al. Nucleic Acids Res. 40, D1016-1022 (2012) PubMed

Gender bias: Mutations on the X chromosome could account for the fact that autism is more common in boys than in girls.

TBL1X, a gene located on the X chromosome, is associated with autism in males but not in females, according to a study published 3 November in Molecular Autism¹.

Because autism is roughly four times more common in boys than in girls, several studies have investigated whether mutations in genes on the X chromosome contribute to the disorder.

In the new study, researchers used data from three genetic databases to look for variants in the X chromosome that are associated with autism.

The study included a total of 5,856 individuals from 1,456 families that have one or more children with autism, from two different sources: the John P. Hussman Institute for Human Genomics in Miami and the Autism Genetic Resource Exchange. It also looked at 1,204 individuals with autism and 6,472 controls from the Autism Case-Control Study, which houses data from multiple sites across the United States.

Altogether, the researchers analyzed nearly 11,000 single nucleotide polymorphisms, which are alterations to single DNA bases, on the X chromosome.

The researchers analyzed data from the 1,204 individuals with autism the same way they analyzed the family data, by treating the individuals as members of theoretical families with missing parental data.

The analysis also produced separate results for males and females. Most studies separate the two categories at the outset, which limits the analyses to siblings of the same gender and lowers the studies’ statistical power, the researchers say².

Based on their analysis, they linked a variant in one gene, TBL1X, to autism, but only in males.

The variant is associated with autism when the results from the three datasets are combined, the study found. This variant is also associated with autism in the individual data alone, and nearly met statistical significance with the family data. It is difficult to reach an association for a rare variant with so few participants, the researchers say.

TBL1X is involved in the Wnt signaling pathway, which is important in brain development and has been implicated in autism and schizophrenia. Engrailed 2, a gene whose expression is regulated by the Wnt pathway, is also associated with autism.

TBL1X is located five megabases from neuroligin 4X, which codes for an autism-linked protein that functions at the junctions between neurons. It is also found within deletions of this region that are associated with autism³.

References:

1: Chung R.H. et al. Mol. Autism 2, 18 (2011) PubMed

2: Chung R.H. et al. Am. J. Hum. Genet. 80, 59-68 (2007) PubMed

3: Thomas N.S. et al. Human Genetics 104, 43-48 (1999) PubMed

As anyone who’s read Shakespeare, seen the Twilight movies or trudged through junior high school knows, there is no social interaction more maddeningly complex than romantic love.

So someone with autism, who presumably lacks the ability to understand others' thoughts and feelings, couldn’t possibly manage a meaningful relationship. Right?

In fact, many people with autism forge deep romantic relationships, as I learned last month from an engaging New York Times profile of two teenagers with Asperger syndrome.

The couple, Kirsten and Jack, live together and are in love — and they’re not all that unusual, according to the article. There are apparently large online communities devoted to helping people with Asperger syndrome find dates and improve their intimate relationships.

Like any couple, Kirsten and Jack’s relationship has its ups and downs. Their autism diagnoses make certain things easier. They bond over their shared interest in science, and don’t have to hide their repetitive behaviors. They each say exactly how they feel — no games, no passive aggression, no agonizing over what kind of Christmas present to buy.

But she has trouble keeping her emotions in check, leading to tearful breakdowns over how to cut cauliflower or his refusal to get a cat. They have different sensory preferences: He hates kissing and holding hands and likes to be softly petted, whereas she likes to be squeezed deeply and yearns for more physical affection.

Each struggles to understand what the other one is thinking — a skill called theory of mind. Since 1985, researchers have known that this ability is impaired in most people with autism. Studies have found that its absence not only impedes social communication in people with the disorder, but can affect their moral reasoning and even the way they structure sentences.

That said, theory of mind seems to be more nuanced in some people with high-functioning autism or Asperger syndrome. A couple of years ago, a study in Science suggested that although they don’t automatically grasp what other people are thinking or feeling, they can learn the skill over years of real-world practice.

That may be why Kirsten and Jack are making it work. It seems that a big part of their success is the help they’ve received from books, online forums and therapists. Kirsten’s therapist, for example, taught her that when she is in a bad mood, she should try to focus on her favorite character from the television cartoon My Little Pony, who always makes her laugh.

This is all encouraging, particularly because so little is known about how adults on the autism spectrum fare in life. The article suggests that, if they want to and receive the right guidance, adults with autism can not only live independently and find jobs, but also commit to a partner.

Besides, it’s not as if romantic relationships between people who don’t have autism are all sun and roses. As the Bard wrote: “The course of true love never did run smooth.”