OLDER fathers may face an increasing risk of having children with psychiatric problems, including bipolar disorder, autism and attention deficits.
American and Swedish researchers examined data on more than 2.6 million Swedes born from 1973-2001, in the largest study of its kind to date.
Men who fathered kids after age 24 faced increasing odds for having children with psychiatric problems or academic difficulties, with the greatest risks seen at age 45 and older.
The results add to evidence challenging the notion that men’s sperm are timeless.
The increased risk to children born to fathers aged 45 and older versus those aged 20 to 24 was surprising, said lead author Brian D’Onofrio, an associate professor in the psychological and brain sciences department at Indiana University.
Compared with children of the youngest men, those fathered by over-45s faced risks almost 25 times greater for bipolar disorder; 13 times greater for ADHD; more than three times greater for autism; almost three times greater for suicide attempts; and about twice as great for schizophrenia and substance abuse.
Absolute risks were still small — less than one per cent of children of older dads had autism, attention deficit-hyperactivity disorder or bipolar disorder; and less than four per cent had schizophrenia or fell victim to substance abuse or attempted suicide.
Academic difficulties were more common, although they still did not affect most children of older fathers.
Dr D’Onofrio said the researchers took into account several factors that could have influenced the results — including the mothers’ age at conception, parents’ education and history of psychiatric problems, and siblings’ health — and still found strong risks linked with older men.
“People frequently ask me, ‘What’s the safe age to father children?’, but the answer isn’t clear-cut,” said Dr D’Onofrio. “There is no threshold where on one side it’s safe and on the other side it’s problematic.”
Molecular geneticist Simon Gregory, an associate professor at Duke University, called the new study impressive because of its size and depth. The authors had access to a registry of most births in Sweden over more than 20 years, along with reams of data on psychiatric treatment, education and social welfare.
The study was published online in JAMA Psychiatry, but this type of research is not proof on its own.
“There’s no reason to ring the alarm bells that older men shouldn’t have kids,” said Dr Gregory, stressing that the results would need to be replicated in additional research and molecular evidence found.
He is among scientists who think the reason risks may increase with advancing age is that sperm are continually produced throughout men’s lives and mutations may occur each time cells divide to create new sperm.
By contrast, women are born with a set number of eggs that become susceptible to certain genetic mutations, including those that cause Down syndrome, as women age. Other research has suggested women’s age might play a role in autism and other disorders, but fathers’ advanced years were not considered a potential risk until fairly recently.
Dr Christopher Pittenger, a Yale University expert in psychiatric disorders, called the results convincing and said it is likely that many genetic mutations linked with older age contribute to the conditions studied, but that other factors also play a role.
Comment: Wouldn’t it be interesting to turn this argument around, in a culture where we have a kind of institutionalised and homogenised view of life?
For example, what if these tendencies in children actually indicated the creative end of the spectrum and that the psychiatric way of looking at them is only one perspective… and an institutionalised one at that. If so, maybe the older fathers are ‘passing down’ their increased knowledge and wisdom, which may make their offspring ‘non-conformists’.
All we ask here is that this kind of evidence is not simply taken on face value, but is explored from other perspectives to get a fuller picture.