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Magdalena Janecka, Ph.D., of the Icahn School of Medicine at Mount Sinai, N.Y., and colleagues analyzed data from the medical and psychiatric records of nearly 1.5 million people in Denmark who were born between 1980 and 2007. They looked at rates of autism spectrum disorders (ASD), attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), and Tourette’s syndrome/chronic tic disorder (TS/CT). They then looked at the age of the parents at the time people with these disorders were born. Parents who were younger than 27.5 years were considered “younger,” and parents older than 37.5 years were considered “older.”
The researchers found that children born to older mothers had a 34% increased risk of developing ASD, and children born to older fathers had a 26% increased risk of developing ASD. Children born to older mothers had a 23% increased risk of developing OCD, whereas a father’s age did not appear to significantly affect risk.
“Many epidemiological studies have indicated that advancing parental age, and, in particular, advancing paternal age, contribute to offspring risk for ASD and other neuropsychiatric disorders,” Janecka and colleagues wrote. “Our study provides robust evidence for distinct patterns of disorder risk associated with early vs. late parenthood, separately in mothers and fathers.”
The researchers also found that children born to younger mothers had a 70% increased risk of developing ADHD, and children born to younger fathers had a 63% increased risk of developing ADHD. Children born to younger mothers had a 12% increased risk of developing TS/CT, and children born to younger fathers had a 9% increased risk of developing TS/CT.
“Compared to children of older parents, those born to young parents are more often exposed to disadvantageous home environments and parenting behavior,” the researchers noted. “These environmental factors have been associated with higher risk for ADHD and TS/TC, and with regard to ADHD, could account for the shared parental contribution we observed.”
The researchers added that their results could provide insight on other disorders.
“In the light of the heterogeneity of these disorders, it is … plausible that parental age exerts its effects on any given disorder via a number of different routes—for example, the association between paternal age and ASD could be due to considerably different mechanisms in sporadic and familial cases,” they wrote.
(Image: iStock/Vagengeym_Elena)
