Confirmed: Kids of Older Dads At High Risk of Mental Illness. But Why?

By Valerie Ross | August 29, 2011 4:22 pm

Children of older mothers, scientists have long known, are at higher risk for certain genetic disorders such as Down syndrome. But the father’s age is matters, too. As a father’s age increases, research shows, so does his child’s risk of mental illness, schizophrenia and autism in particular. In Scientific American, Nicole Grey explores the link between a father’s age and his child’s health, as well as the tricky questions about what mechanisms are behind the that link: genes, epigenetic changes, environment, or some combination of the three.

Some researchers suggest that epigenetic changes, alterations in how genes are expressed, that occur over a man’s lifetime may be passed down to his children, triggering such diseases, or that genetic mutations in sperm may make children more vulnerable to developing psychiatric disorders, rather than directly causing the condition. And for all the worry about genetic changes in a woman’s eggs once she passes 35, a man’s sperm has ample opportunity to accumulate mutations, too:

When it comes to reproductive outcomes, older men are actually disadvantaged compared with older women, due to the high rate of sperm cell division. [Psychiatry professor John] McGrath points out that during a woman’s lifetime, her oocyte cells divide only 23 times. Women are born with all of the eggs they will ever carry. Once boys hit puberty, their sperm cells divide every 16 days. “By the time a man is 40, his sperm cells have undergone 660 cell divisions, and 800 cell divisions by age 50,” he says. More divisions translate into a higher risk for genetic alterations.

Read more at Scientific American.

Image courtesy of misspudding / Flickr

CATEGORIZED UNDER: Health & Medicine, Mind & Brain
  • Greg King

    It seems to me that epigenetic causes are more likely. If it’s simply random genetic mutations, wouldn’t any factor be equally at risk, not just mental disorders? Also, it would be a lot easier to just sequence the genome of the children and see if any mutations have accumulated, that’s a cheap and viable option within the next few years if not now.

  • badnicolez

    Could people waiting to have kids until their thirties and forties explain the spike in autism rates? That would be quite a blow to the anti-vax community. Cumulative genetic damage is the main reason I’m not having kids since I didn’t do so in my twenties.

  • Rob

    @badnicolez – It’s people like you that should have kids. You seem to employ rational thought, think beyond yourself, and actually care about the outcome. The benefit outweighs the risks. Civilization needs people like you to reproduce and help their kids grow to become good people too. I’m afraid that the more analisys intelligent and kind people put toward reproduction, the lower the reproduction rate becomes in that population.

  • Methuselah

    And that’s why older men should pair up with much younger women (if they decide to pair up in the first place) to balance out the genetic risks. Same for older women and much younger men.

  • Gretchen

    @ Rob – It’s clear that badnicolez has found ways apart from parenthood to contribute to the sanity side of the scales. Admirable in my book.

  • John M. Tax

    I’d like to see a graph plotting age of male vs incidence of abnormalities.

  • Sandra Langstaff

    Does this mean that within a large family, the youngest sibling would have the greatest risk for mental illness? If so, I’m surprised that in other more general psychological studies this hasn’t been found before now.
    Also, I wonder what they define as an ‘older’ dad?
    @badnicolez : here is a link to an article de-bunking the Autism-caused-by-vaccination myth:

  • Pippa

    I agree, Rob. We shouldn’t forget that the ‘risk’ of having a perfectly normal typical child is very high – most older Dad’s have kids that have no problems at all. Furthermore autistic children can grow up to be fascinating adults – Einstein comes to mind. My son was classically autistic and, yes, he did give us a run for our money and was a lot of hard work to raise, but now he is in University and on the Dean’s list every year so far. If I had screened him out or avoided having him the world would be a poorer place. He’s still more than a bit eccentric but people tend to assume that’s just because he’s so bright. So, go for it, badniscolez.
    Women can look up the absolute risk of having, eg a downs syndrome baby at each age so men should get the same stats when they are choosing parenthood.


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