Mohammad Hossein Rahbar, professor of epidemiology and biostatistics at the University of Texas School of Public Health, and the University of the West Indies, Mona Campus, Kingston, Jamaica, compared 68 age- and sex-matched, case-control pairs of mothers and fathers.
"This should put to rest discrepancies in previous studies showing that just maternal age or just paternal age are linked to having a child with autism," Rahbar said in a statement. "Our results revealed that the age of the father and the mother are jointly associated with autism in their children."
The study, published in the Journal of Autism and Developmental Disorders, found that mothers who had children with autism were on average 6.5 years older than women who did not have a child with autism, while the corresponding age difference for fathers was 5.9 years.
In previous studies, Rahbar said that because of the statistical models used, it was hard to assess both maternal and fraternal age as joint risk factors, but by using complex statistical models he avoided the problem.