Children of men over 40 have a significantly higher risk of autism than those fathered by younger men, according to a study in the September issue of the journal Archives of General Psychiatry.
Lead author Abraham Reichenberg of Mt. Sinai School of Medicine in New York and the Institute of Psychiatry, King's College, London evaluated the age-related association in Israeli children born in the 1980s. "The offspring of fathers who were forty years or older were almost six times more likely to have autism than the offspring of fathers who were younger than thirty years of age," he says. "We don't know yet" why this is true, he adds, noting that older fathers have also been associated with other neurological and psychiatric conditions. "So with age," he observes, "there is a higher likelihood for errors to accumulate in the male sperm, and that might be transferred to the offspring."
Reichenberg says better understanding of that genetic transfer could provide a clue about how brain disorders like autism develop and which genes are linked to the condition.
"The paternal age might target specific genes. It might suggest looking for mutations," he says. "Or it might suggest that there are other processes that might be flawed with older age. We know a little bit about those processes in genetics and we might start looking if those specific processes are also linked to autism."
According to the study, the mother's age was not a factor associated with autism. Reichenberg says the research adds to recent observations that men - like women - have 'biological clocks' for producing healthy babies.