The children of men aged 40 and older have a significantly increased risk of having autism spectrum disorders compared with those whose fathers are younger than 30 years, say doctors writing in the Archives of General Psychiatry. Autism and related conditions, known collectively as autism spectrum disorders, have become increasingly common, affecting 50 in every 10,000 children, as compared with 5 in 10,000 twenty years ago. Health experts speculate that the increase is partially due to higher levels of awareness and changes in diagnosis processes, but could also reflect an increase in incidence of autism. While parental age has previously been linked to abnormalities in the brain development of children; this is one of the first studies to gauge the effect of mothers' and fathers' ages on autism.
Conducted by Abraham Reichenberg, Ph.D., of the Mount Sinai School of Medicine, the study found that advancing age among fathers was associated with an increased risk of autism. This association persisted after the researchers controlled for year of birth, socioeconomic status and the mother's age. Specifically, the odds of autism spectrum disorder were nearly six times greater among children of men aged 40 and older, than those of men 29 years and younger. Interestingly, older age among mothers was found not to be associated with autism.
Speculating on the mechanisms that might be behind the paternal age effect, the researchers cited spontaneous mutations in sperm-producing cells or alterations in genetic "imprinting," which affects gene expression. "Although further work is necessary to confirm this interpretation, we believe that our study provides the first convincing evidence that advanced paternal age is a risk factor for autism spectrum disorder," they concluded.
Source: Journal of the American Medical Association
