The study confirms previous, smaller studies that found that psychiatric disorders were more common among blood relations of people with autism. A strong genetic component is suspected for autism, a developmental disorder.
"The study . . . will stimulate further research by its suggestion that mental disorders are more complex than our simple-minded categorical approach to diagnosis," Shaw said. "Boundaries between diagnoses are less clear, and we need to take a more developmental approach to our understanding of psychiatric illness if we want to understand their complexities."
"I do think it will help us redefine the case definitions [of autism]," Daniels added.
A second study in the same issue of the journal found that children whose mothers had certain infections during pregnancy (bladder infection, diarrhea, cough or vaginal yeast infection) were more likely to develop epilepsy.
The exact reasons for the association are unclear, said a group of researchers based in Denmark, but there is some evidence to suggest that infections occurring during pregnancy may interfere with fetal brain development.
Visit the U.S. National Institute of Neurological Disorders and Stroke for more on autism.
SOURCES: Jon Shaw, M.D., director and professor, division of child and adolescent psychiatry, University of Miami Miller School of Medicine; Julie L. Daniels, Ph.D., assistant professor, epidemiology and maternal and child health, University of North Carolina, Chapel Hill; May 2008 Pediatrics
All rights reserved