Children with old fathers more likely to have psychiatric disorder

Advancing paternal age leads to higher rates of psychiatric and academic problems than previously estimated, according to a new study by researchers at Karolinska Institutet and the University of Indiana. The findings are presented in the journal JAMA Psychiatry.

With comprehensive records – everyone born in Sweden from 1973 until 2001– the international research tem have documented a compelling association between advancing paternal age and numerous psychiatric disorders and educational problems. The disorders included autism, ADHD, bipolar disorder, schizophrenia, suicide attempts, and substance abuse problems. Academic problems included failing grades, low educational attainment, and low IQ scores.

The results show that when compared to a child born to a 24 year-old-father, a child born to a 45-year-old father is 3.5 times more likely to have autism, 13 times more likely to have ADHD, two times more likely to have a psychotic disorder, 25 times more likely to have bipolar disorder, 2.5 times more likely to have suicidal behavior or a substance abuse problem. For most of these problems, the likelihood of the disorder increased steadily with advancing paternal age, suggesting there is no particular age at which advancing paternal age suddenly becomes problematic.

“It is important to recognize that the findings do not determine every child born to an older father to get these problems”, comments co-author Paul Lichtenstein, Professor at the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet. “Instead, this new knowledge can be helpful in decision making on a personal level, as the average age for childbearing has been increasing steadily for both men and women during the last decades. “

He points out that existing studies in this research filed suggests an increasing risks for some psychological disorders with advancing paternal age. Yet, the results are often inconsistent with one another, statistically inconclusive, or unable to take certain confounding factors into account. In the current study, the results are more consistent and based on a larger population than earlier studies. The researchers were also able to control for many other factors than paternal age that earlier studies could not.

For example, by comparing cousins, including first-born cousins, the researchers could examine whether birth order or the influences of one sibling on another could account for the findings. Further, the authors statistically controlled for parents’ highest level of education and income, factors often thought to counteract the negative effects of advancing paternal age because older parents are more likely to be more mature and financially stable.

“Our study does not say anything about the reasons for this increasing risk of psychiatric and academic problems in the offspring of elderly fathers”, says Paul Lichtenstein. “However, molecular genetic studies have shown that sperm of older men have more genetic mutations.”

The research was funded with grants from the National Institute of Child Health and Human Development, the Swedish Research Council, and the Swedish Council for Working Life and Social Research.

Publication

Parental Age at Childbearing and Offspring Psychiatric and Academic Morbidity
Brian M. D'Onofrio
JAMA Psychiatry, online 26 February 2014