A study of the children of older fathers has found subtle impairments of intelligence and other mental abilities during infancy and childhood.

The story has been widely reported, but the findings have not been put in the proper context. This is only the latest in a series of problems identified in the children of older fathers, an area of study that has been widely overlooked.

The risks faced by the children of older fathers are similar to those faced by the children of older mothers. But while we all know about the risks of Down syndrome in older mothers, most of us are ignorant of the risks in the children of older fathers.

And the risks for older fathers are comparable to those for older mothers. As I noted in The Father Factor, an article on this subject in the current issue of Scientific American Mind, Children born to fathers 40 or older have nearly a six-fold increase in the risk of autism as compared with kids whose fathers were younger than 30. Children of fathers older than 50 have a nine-fold risk of autism.

And advanced paternal age, as it's called, has also been linked to "an increased risk of birth defects, cleft lip and palate, water on the brain, dwarfism, miscarriage and ‘decreased intellectual capacity.'"

And to an increased risk of schizophrenia. This risk rises for fathers with each passing year. The child of a 40-year-old father has a 2 percent chance of having schizophrenia-double the risk of a child whose father is younger than 30.

And the kicker: A 40-year-old man's risk of having a child with schizophrenia is the same as a 40-year-old woman's risk of having a child with Down syndrome.

More recent studies have linked fathers' age to prostate and other cancers in their children. In September 2008, researchers linked older fathers to an increased risk of bipolar disorder in their children.

Add to that the new finding, that the kids of older fathers score lower on IQ and other cognitive tests. The study, in the current issue of PLOS Medicine, noted that the cognitive deficits were small, and that the children of older fathers might "catch up" to their peers as they get older. But nobody knows whether these early deficits might have implications for the children's development across their lifespans, the authors said.

So why don't we hear more about the risks faced by the children of older fathers? Why isn't it part of the discussion about whether, and how long, to delay child-bearing?

"I think there has been a bit of a cultural bias against even looking at this issue," says Dr. Dolores Malaspina, a professor of psychiatry at New York University Medical Center who has done much of the pioneering research on this. "It turns out that the optimal age for being a mother is the same as the optimal age for being a father," she told the New York Times.

Do the findings offend middle-aged men's sense of themselves, of their vitality and power? Do they puncture the image of the father as defender of the family?

These risks should be understood by every older father who's considering having children.

Be sure to read the following responses to this post by our bloggers:

Older Fathers Take Note: A Reply to Paul Raeburn is a Reply by Timothy A Pychyl Ph.D.

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