• Deficiency in folic acid intake before conception (American
Journal of Clinical Nutrition, Schmidt, et al. 2012).
• Mother’s exposure to pesticide (Environmental Health
Perspective, Shelton, et al. 2012).
• Mother’s exposure to air pollution (Environmental Health
Perspective, Volk, et al. 2011).
• Obesity in the mother (Pediatrics, Krakowiak, et al. 2012).
Another risk is having a sibling with the condition. Scientists
have long documented that autism can run in families:
estimates are that a sibling of an ASD child has an increased risk
of 3 percent to 10 percent of having the disorder. But last year, a
larger sample and more thorough study in Pediatrics (Ozonoff,
et al.) determined that the sibling recurrence rate is much
higher, with nearly one in five siblings likely to develop autism.
This finding again underscores the need for increased
vigilance in monitoring and screening at-risk infants as early
as possible, when their brains are more malleable, says study
co-author Wendy Stone, PhD, professor of psychology who
directs the University of Washington Autism Center. “If we
can begin intervention for high-risk children in the first or
second years of life, we may find the effects are much more
powerful,” Stone says.
Another study (Molecular Psychiatry, Constantino, et al. 2012)
showed that half-siblings are also at risk. By examining half-siblings, researchers were able to show that mothers and fathers
appear to transmit genetic risk equally in families where autism
recurs. Researchers compared the genetic structure of the maternal
half-siblings with autism with that of the full siblings with autism.
The risk was about half of what they saw in full siblings.
Psychologists can help parents identify ASD early on by
teaching them how to observe and look for behavioral signs of
the condition, says Rogers, who also co-authored the Pediatrics
study. These signs typically involve lack of interaction —
not initiating or responding to cuddling, for instance, or not
responding to his or her name or not smiling by 9 months of age.
Knowing about the elevated risk for siblings of children
with ASD also raises the issue of genetic counseling, she adds.
Psychologists may want to suggest this option to families who
Early brain development
Could ASD be diagnosed even earlier? The answer appears
to be yes. More sophisticated brain imaging technology such
as functional MRI has enabled scientists to trace infants’
neurodevelopment. In one study (American Journal of
Psychiatry, Wolff, et al. 2012), also co-authored by Dawson and
Joseph Piven, research professor of psychiatry at University of
North Carolina at Chapel Hill, researchers compared the brains
of infants who had siblings with autism with those of infants
who did not have that high-risk factor. The study, employing
diffusion tensor imaging, identified marked differences in
the white matter (fibers that surround neurons and support
transmission of neural signals) among high-risk six-month-
Autism prevalence and the DSM
Are autism spectrum disorders (ASD) really
more prevalent or are we just better at
collecting the data and identifying the disorder
at younger ages?
“It’s likely both,” says Judith Miller, PhD,
training director at the Center for Autism
Research, Children’s Hospital of Philadelphia.
Also contributing to the increased number of
diagnoses is heightened awareness of subtle
forms of ASD and broader application of the
diagnostic criteria, she adds. Then factor in new
data suggesting that 15 percent to 30 percent
of autism cases may be due to the increasing
average age of new fathers (see main story).
When it is released next year, the Diagnostic
and Statistical Manual of Mental Disorders- 5 is
expected to combine the subgroups of Asperger’s
syndrome, pervasive developmental delay (PDD)
and autistic disorder into one broad category —
autism spectrum disorder, or ASD. While some
wondered if combining the criteria for these
subgroups in DSM- 5 would lead to fewer people
being diagnosed with autism, a study this year
in the Archives of General Psychiatry (Lord)
suggested it will have little effect in that regard.
Further, the data collected from 12 university-based sites suggests that removing these
subtypes will make it easier to make accurate,
consistent ASD diagnoses, says study co-author
Ellen Hanson, PhD, a psychologist and research
lab director at Boston Children’s Hospital.
On a practical level, having one overarching
diagnosis in DSM- 5 may help some people with
ASD access additional treatment and support,
Hanson notes. People with diagnoses such as
Asperger’s have not always been eligible for
olds who would later develop ASD. These changes were seen six
months to a year before affected children typically show the full
range of outward signs of autism.
Stone hopes such findings will herald a new ASD risk-
prevention model. “By developing new ways of working with
very young children, we hope to change their brain architecture
and improve their developmental course,” she says.
In other work, researchers are learning more about
interactive strategies parents can use to help at-risk infants in the
first year of life. “A child of 11 months is too young to participate
in structured behavioral therapy, but parents are in a position to