Recent advances in artificial reproductive therapies and IVF have enabled older mothers and fathers to create and carry a pregnancy to fruition, but there are major risks involved. Until recently, those risks were thought to stem solely from the decreased quality of maternal eggs. But a new and impressive study strongly suggests that a father’s age can also contribute to mental illnesses such as bipolar disorder, schizophrenia, attention deficit disorder and autism spectrum disorder (ASD). Men who postpone fatherhood into their 30s and beyond, or who are considering starting a second family, now need to be aware of the risks.
A quick biology lesson: Women are born with all the eggs they will ever have. Once menstruation starts, the ovaries release one egg every 28 days. These eggs deteriorate over time, so that by age 40, only a small minority of them is healthy enough to successfully host a fertilizing sperm cell.
Men, on the other hand, produce sperm cells through ongoing cellular replication. A spermatocyte replicates itself, spinning off a viable sperm cell, every 16th day. By age 20, the spermatocyte has replicated 200 times, creating 200 new sperm cells for fertilization. By age 40, it will have done so 660 times, and by age fifty, 840 times.
Here’s the problem: Every time the spermatocyte splits, there’s a chance of a mutation to the cell’s DNA, especially if the cell is unable to repair itself due to the metabolic influence of pollutants, a high sugar/carbohydrate diet, cigarette smoking, obesity, hypertension and other health issues. Called de novo or copy-error mutations, these DNA mutations occur about twice annually.
We have always known that, with age, male sperm cell production declines. Thanks to an important new study led by Indiana University professor Brian D’Onofrio, we now also know that the quality of the DNA is compromised. D’Onofrio and a team of researchers analyzed the health records of some 2.6 million Swedes born between 1973 and 2001 (Swedes keep more detailed medical records than Americans do). They found that fathers older than 45 were three times more likely to have children who suffered from autism than fathers aged 20 to 24. The incidence of schizophrenia and attention deficit disorder in these children was also substantially increased. The risks were still relatively low—for autism, say, 1 in 100 versus 1 in 300—but the risk had clearly increased.
Now that we know the importance of paternal age, prevention strategies should take a threefold approach:
01. Earlier procreation.
Paternal DNA appears to peak in men aged 25 to 30. Now that we know the health benefits of younger parenting, I can imagine a social swing back towards having kids early among the very same people who are now postponing parenthood.
02. Proactive DNA injury prevention.
Men should start to protect their DNA by leading healthy lives, limiting the metabolic damage induced by overeating, smoking, high sugar/carbohydrate diets and other unhealthy behaviors.
03. Genetic counseling .
Though no reliable commercial product exists to predict the risk of mental disorders, genetic counseling can help evaluate each case.
This field of medicine is still young, and a time may come when the cumulative damage of a lifetime can be better managed. Someday, men in their 20s may choose to have their sperm frozen for future use (very, very few healthy men do it today). Until then, though, potential fathers and mothers can best help their children-to-be by keeping themselves as healthy as possible. Acting in your own self-interest turns out to be good preparation for parenting.
