If the general public understanding of autism is wanting, it may be because researchers are still struggling to understand the disorder themselves.

While all autistic individuals have problems with social interactions and have restricted or repetitive behaviors, autism encompasses a wide range of abilities and disabilities. A small percentage of autistic people have excellent memories. Another minority have exceptional musical or artistic skills. And recent estimates suggest that nearly half of those with autism have average to above-average IQs.

In all its variability, autism presents science with a moving target. Researchers struggle to pin down how brain mechanisms, genetics, environmental conditions, and other factors combine to produce the disorder in an individual.

A team of researchers at the University of Pittsburgh in the US, headed by Carla A. Mazefsky have trained their attention on the families of autistic people. They were specifically interested in whether something about these families might account for the behavior of their relative with autism.

They collected information on 77 individuals (aged between eight and 39) with average or better intellectual ability and autism. Their parents answered questions about the autistic individual’s behavior and family history, including whether other members experienced psychiatric disorders.

They found that the autistic participants in the study who had poor daily living skills (such as difficulty with personal self-care) and who had greater difficulty with interpersonal and coping skills were more likely to have a family history of depression and shyness than participants with fewer of these problems.

Mazefsky and her colleagues suggest that the link between family history and autistic people’s adaptive skills could certainly be genetic. In other words, some constellation of genes leads to depression for some family members and poor adaptation for relatives with autism.

But other factors could be at play. They speculate, for example, whether having parents or other family members who are depressed can increase the stress level in the household, which, in turn can affect behavior. Depressed or abnormally shy family members might be poor models of adaptive behavior for people with autism. Additionally, depressed caregivers might marshal fewer resources to help an autistic child.

The researchers stress the need for more research to understand how family history might contribute to autistic children’s struggles and how enhancing family functioning might improve the prospects for those with autism.

[See also: Autism research advances but cure still far away]

• Summary of “Variability in Adaptive Behavior in Autism: Evidence for the importance of family history” by Carla A. Mazefsky, Diane L. Williams and Nancy J. Minshew in Journal of Abnormal Child Psychology, Volume 36, Number 4, May, 2008, pp 591-599.