Father’s age linked with decreased fertility and greater risk of disorders in offspring

Two recent studies confirm the link between paternal age and fertility outcomes.  The longer a man delays fatherhood, the poorer the quality of his sperm. Children fathered by older dads also appear to have an increased risk of developing autism, schizophrenia, attention deficit hyperactivity disorder (ADHD), and bipolar disorder.

The first study was conducted in Iceland and published in the journal Nature. The researcher sequenced the DNA of 78 parents and their children and found a direct correlation between the father’s age, and the number of gene mutations linked to autism spectrum disorders and schizophrenia. The researchers found that 97% of all gene mutations came from the father, and that the mother’s age had no impact on the risk. Dr. Kari Stefansson, of Decode Genetics, who led the study stated:

“Society has traditionally been very focused on the age of the mother. But it seems that disorders such as schizophrenia and autism are actually influenced by the age of the father and not the mother.”

Another study recently published in the JAMA Psychiatry journal, led by researcher Brian D’Onfrio at Indiana University in the US, further underscores the potential dangers of advanced paternal age as well. The researchers studied people born in Sweden from 1973 to 2001 and estimated the risk of psychiatric problems such as autism, bipolar disorder attention deficit hyperactivity disorder (ADHD), and academic performance problems. The study found that children conceived when fathers were age 45 and older were 3.5 times more likely to have autism compared with fathers aged 20-24. Those born to older fathers had 13 times greater risk of developing ADHD, 24 times greater risk of developing bipolar disorder, and double the risk of suicide attempts and substance abuse. There was also a higher risk of academic difficulties. D’Onfrio said that they were “shocked” by the findings, which suggest that the magnitude of the risks associated with advanced paternal age is much greater than previously estimated.

Men continue to make new sperm across their lifetime. Every 16 days, cells in the testicles divide and DNA in each cell is copied into a new cell, which is used to make new sperm. Professor Andrew Wilkie, a clinical geneticist as the University of Oxford, says as a man ages, it is more likely that some sperm will be made containing an error in the DNA – what’s known as a “genetic mutation.” If this mutated sperm is used to form a fetus, there is more likelihood that there will be problems in its development.  Dr. Allan Pacey, the UK’s leading authority on male fertility suggests that:

“…it’s time for a wake-up call on the dangers of putting off becoming a dad…my advice is for men to have children as young as possible – don’t wait until you’re in your 50s. It will make all the difference in the world to your children’s health.”

Read more about male age and fertility here, here, here, and here.

Read more about the studies here and here. 

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