Do men have biological clocks as new autism finding suggests?

By Deborah Kotz, Globe Staff

After reading news reports linking a baby’s risk of having autism with the father’s -- not mother’s -- biological age, I’m guessing women felt a little vindicated; finally, researchers have acknowledged that we’re not the only ones with a biological clock that’s ticking away.

The study, published Wednesday in the journal Nature, found that the number of DNA changes or mutations increase with age making it more likely for older fathers to pass along mutations involved in autism or schizophrenia. While a young 25-year-old father passes along an average of 25 new mutations to his child via his sperm, a 40-year-old transmits 65 mutations. Moms, on the other hand, transmit an average of 15 new mutations regardless of their age, the Icelandic researchers found.

And the solution seems so simple: “Collecting the sperm of young adult men and cold-storing it for later use could be a wise individual decision,’’ Alexey Kondrashov, a professor of evolutionary biology at the University of Michigan in Ann Arbor, wrote in an editorial that accompanied the study.

So, are moms really off the hook when it comes to determining autism risk, and should young men really think about banking their sperm just as women have been told to consider egg freezing to preserve their fertility?

“Banking sperm doesn’t sound like the worst idea,” said Dr. Martha Herbert, a pediatric neurologist at Massachusetts General Hospital and author of The Autism Revolution. “But there’s also no reason to panic since these types of mutations probably play a minority role in the development of autism.”

Age certainly can increase genetic mutations, but so can a variety of lifestyle factors including smoking and having a poor diet that’s lacking in nutrient dense foods like fresh fruits and vegetables, fish, and whole grains. “A diet high in sugar, fast food, and packaged goods increases harmful inflammation,” said Herbert. This same process that’s thought to be involved in obesity, she added, also can damage a cell’s DNA.

Previous research has shown that any sort of stress on the body -- from a strenuous job to lack of sleep -- can also increase genetic damage, and they, too, could play a role in determining autism risk.

Intense exercise might be another good thing to avoid, said Herbert, since it can overtax the body leading to DNA damage that might also increase autism risk in babies conceived by strenuous fitness buffs. Men, in particular, have been drawn to “extreme” workout videos and boot-camp classes that extol the benefits of getting the heart to pump at or near its maximum rate for an extended period of time.

Researchers are starting to explore whether this extreme form of exercise causes more harm than benefits, according to Herbert, especially following the sudden death in May of 58-year-old ultramarathon runner Micah True from heart failure.

Other factors that contribute to autism occur in the womb, while the fetus is growing -- so moms, you’re not off the hook. Certain genes are programmed in the womb depending on the environment that a baby is bathed in. “We don’t know the extent that diet and lifestyle predicts mental disorders in children,” said Herbert, “but I wouldn’t want to tell a mom that it’s totally irrelevant; she needs to eat really well and be moderately active before she conceives and while she’s pregnant.”

Deborah Kotz can be reached at dkotz@globe.com. Follow her on Twitter @debkotz2.