For years, psychiatric disorders that developed in children have been linked to the mother’s genes. But growing evidence now seems to suggest that a number of factors in fathers play a larger role in the development of psychiatric issues in their offspring.
A new study published Wednesday in JAMA Psychiatry found that children who are born to fathers older than age 45 may be at higher risk for disorders like autism, ADHD, psychosis, and bipolar disorder compared to children born to younger fathers. They also tend to do worse in academics, be involved in drugs, and attempt suicide, the study conducted by researchers in Sweden found.
The study is the largest to date looking at the relationship between a father’s age and their child’s development. The findings are especially interesting given that more couples are waiting until they’re older to have children. The primary motivations for that include financial stability and the generational social shift of couples holding off marriage until at least their 30s. On average, however, U.S. married men have their first child by age 25, while the average age of single men as first-time fathers is 22, according to the U.S. Department of Health and Human Services.
The researchers analyzed more than all births in Sweden between 1973 and 2001, which accounted for about 2 million people. The researchers looked at the fathers’ ages, and estimated the child’s risk for a psychiatric disorder by looking at their siblings and cousins, because they tended to share the same environment. Children born to fathers who were age 45 or older were 13 times more likely to have ADHD, and 25 times more likely to have bipolar disorder compared to children born to fathers who were 20 to 24-years-old. They were also more than twice as likely to have autism or a psychotic disorder like schizophrenia, have substance abuse problems or attempt suicide, and nearly twice as likely to fail a grade or drop out of school compared to children born to younger fathers. The older the father, the higher the risk, the study found.
More attention seems to be paid to a mother’s age during pregnancy mainly because there are immediate risks involved to both the mother and the baby. Pregnant women older than age 35 are an increased risk for developing disorders during pregnancy such as gestational diabetes and preeclampsia. Their babies are also more likely to be born prematurely. But as researcher look further into the child’s development, a father’s age becomes increasingly important.
"Clarification of the associations with [advanced paternal age] would inform basic neuroscience research, medical practice, and personal decision-making about childbearing," the authors wrote.
The study spotted a link between older fathers and their children’s risk for a psychiatric disorder in their children by observing a large group of people, but that doesn’t necessarily mean that a father’s older age causes these disorders.
Previous studies have found that sperm quality decreases as men age, and it’s likely genetic mutations that develop in sperm could be linked to some cases of psychiatric disorders, according to researchers. But genetics may not be the only explanation. The study found that the youngest fathers in the group also tended to have children who dropped out of school. They study did not look at family dynamic such as whether kids diagnosed with these issues came from a two-parent household, whether they were living in a safe and healthy environment, whether the fathers themselves were educated and provided a model for their children, or other environmental factors which may contribute to their risk.
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