Study looks at how parental age affects the mental functioning of offspring

Dec 15 2008

Tel Aviv University researchers found in several consecutive studies that older dads are more likely to have boys with autism and lower IQs. Most recently, they found that the older a father's age, the greater the chance that his son will display poor social abilities as a teen.

Dr. Mark Weiser from TAU's Sackler School of Medicine and his team of researchers are now studying what causes this phenomenon.

"There is a growing body of data showing that an advanced age of parents puts their kids at risk for various illnesses," says Dr. Weiser. "Some illnesses, such as schizophrenia, appear to be more common the older parents get. Doctors and psychologists are fascinated by this, but don't really understand it. We want to know how it works."

To explore this important question, Dr. Weiser looked at data collected by the Israeli army. Subjects included more than 450,000 male teens, aged 16 and 17. The teens were asked these questions: How many good friends do you have? Do you have a girlfriend? Do you generally prefer to be with or without a group of friends? How often do you go out on Friday evenings? Do you tend to be at the center of a party?

Controlling for the variables of IQ, mother's age, socioeconomic status and birth order, the researchers found that the prevalence of poor social functioning increased by 50% in boys with fathers 45 years old and up.

Dr. Weiser, who also works at the Chaim Sheba Medical Center at Tel Hashomer hospital, cautions that the results are far from conclusive. "It could be that men with poorer social skills get married later in life, and therefore transmit this characteristic to their boys. But our studies attempted to control for this variable by looking at brothers from the same father," he explains.

He also suggests that older men shouldn't change their minds about having children since the statistical risk is relatively minor. "The effects of a father's age on the health of his son are quite small, and many of the most dramatic effects in this study are driven by dads in their 50s," says Dr. Weiser. "The difference in risk between someone who is 35 or 45 is so small that it's irrelevant."

Dr. Weiser continues, "But the findings are interesting for clinicians who are looking at the bigger picture of how parental age affects the mental functioning of offspring and what mechanisms are at play in that functioning." And Dr. Weiser doesn't rule out the possibility that older fathers may have better resources for getting their boys tested for autism when symptoms arise.

Published in Oxford Journal's Schizophrenia Bulletin, the study builds on Dr. Weiser's previous research on parental age, autism and IQ scores.