The baby boomer trend of marrying and having families later than the previous generation was one reason for the most comprehensive study to date on parental age and offspring mental health. The findings—published in the journal JAMA Psychiatry in late February—garnered considerable attention for reporting that children born to middle-aged men are more likely than their older siblings to develop any range of mental difficulties, including bipolar disorder, autism, schizophrenia, attempted suicide, and drug abuse.
The authors of the study, Brian M. D’Onofrio, Ph.D., and Paul Lichtenstein, Ph.D., impressively summarize the data and the feedback they have received since the article was published in “The Age Gauge: Older Fathers Having Children,” the featured Cerebrum article for July.
Over the past 40 years, the average age that men and women start a family has risen fairly dramatically. In the United States, the average age for women having their first baby has gone up almost four years, from 21.5 to 25.4 years old. For men, the average increase is three years.
For research purposes, data sets were not available in the United States, say the authors. But in Sweden and Denmark, records date all the way back to 1955. In Sweden, data was collected for 2.6 million people born from 1973 to 2001. In Demark, a separate study by other researchers included all individuals born from 1955 through 2006, a sample of almost 3 million people.
Referencing the JAMA article, Patrick Sullivan, Ph.D., a professor of genetics at the University of North Carolina, told the New York Times: “This is the best paper I’ve seen on this topic, and it suggests several lines of inquiry into mental illness. But the last thing people should do is read this and say, ‘Oh no, I had a kid at 43, the kid’s doomed.’ The vast majority of kids born to older dads will be just fine.”
The researchers say that they controlled for every factor they could think of, including parents’ education and income. “We spent months trying to make the findings go away, looking at the mother’s age, at psychiatric history, doing sub-analysis,” D’Onofrio told the Times. “They wouldn’t go away.”
The authors recommended that older couples considering having children consult a physician and emphasized that “we think that research can help inform personal decision-making, but no study, set of studies, or science in general should unduly influence the decision of when someone should have children.”