Why do boys get diagnosed with autism four times as often as girls?
New research, including some of the latest data from the International Society for Autism Research annual conference last week, addresses this question, one of the biggest mysteries in this field.
A growing consensus is arguing that sex differences exist in genetic susceptibility, brain development and social learning in autismand they are meaningful to our understanding of the disorder and how it will be treated.
Yale University researchers presented results showing that being female appears to provide genetic protection against autism. Meanwhile, scientists at Emory University showed in preliminary work that boys and girls with autism learn social information differently, which leads to divergent success in interactions with other people.The new data, together with previously published studies, suggest that sex should be taken into account in diagnosing and in creating individualized treatment plans, according to experts.
Autism, a developmental disorder characterized by deficits in social skills and repetitive behaviors, affects more than 1 percent of the population. It has long been known to be diagnosed more often in boys.
Yet girls often appear to have more severe autism. The ratio, about four boys to every one girl overall, becomes even more lopsided when intelligence is taken into account. At higher intelligence levels, boys with autism often outnumber girls eight or 10 to one, say researchers.
Why this ratio exists and how much it is skewed by misdiagnosis or under-diagnosis in girls isn't clear. More and more, however, scientists think the sex distribution is meaningful.
"It's such an important biological cluewhy do we have this excess in boys?" said Geraldine Dawson, the chief science officer of Autism Speaks, a research funding and advocacy group. Sex differences in autism and related disorders were relatively ignored until recently and still aren't well understood. The small number of girls who have the disorder meant that studies often didn't include enough girls to be able to reliably examine sex differences. Often, girls were excluded from studies altogether.
Understanding sex differences is important to getting the right diagnosis and treatment, said Christopher Gillberg, a child and adolescent psychiatry professor at the University of Gothenburg in Sweden. Because experts' understanding of the typical features of the condition is primarily based on research with boys, girls may be missed or misdiagnosed, he said. Some evidence suggests that girls are diagnosed, on average, later than boys.
In addition, the clinical picture for children with an autism-spectrum disorder is often complex. Most have other conditions as well, like attention-deficit hyperactivity disorders, sleep problems or epilepsy, which may affect their functioning, Dr. Gillberg said.
Continued here:
How autism is different in girls versus boys