Older Fathers' Offspring More Likely Bipolar

Editor's Choice
Main Category: Bipolar
Also Included In: Psychology / Psychiatry;  Genetics
Article Date: 02 Sep 2008 - 0:00 PST

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The children of older aged fathers may have an increased risk of bipolar disorder (BPD), according to a report released on September 1, 2008 in the Archives of General Psychiatry, one of the JAMA/Archives journals.

A common and intense mood disorder, people who are bipolar often experience episodes of mania and depression. There are few previously identified risk factors for bipolar disorder, one of which is a family history of psychotic disorders. Even so, many people with BPD have no relatives also suffering from the disease. As a result of its heterogenicity, many attempts have been made to classify BPD, for instance by age of onset.

According to the article, previously, other complex neurodevelopmental disorders, such as schizophrenia and autism, have been associated with an older paternal age. To determine if paternal age was associated with BPD,  Emma M. Frans, M.Med.Sc., of the Karolinska Institute, Stockholm, Sweden, and colleagues examined Swedish registers with a diagnosis of bipolar disorder. Pinpointing 13,428 diseased subjects, five controls were selected for each of the same sex and same birth-year without BPD.

In comparison, as the age of one's father became higher, it became more likely that one was bipolar. When controlling for the age of the mother, those participants whose fathers were older than 29 years had an increased risk of BPD. The authors controlled for many variables through with the association held. "After controlling for parity [number of children], maternal age, socioeconomic status and family history of psychotic disorders, the offspring of men 55 years and older were 1.37 times more likely to be diagnosed as having bipolar disorder than the offspring of men aged 20 to 24 years,"they say. While having an older mother also was associate with increased risk, this was not as strong an association as the paternal effect. If the bipolar disorder was diagnosed before the age of 20, this early onset BPD was much more strongly associated with the father's age and not associated with that of the mother.

The authors note that this association has often been attributed to the personality traits of older fathers. They continue, "However, the mental disorders associated with increasing paternal age are under considerable genetic influence." This indicates that a genetic link may exist between the age of a father and the diagnosis of bipolar or other disorders in his children.

The authors suggest a mechanism for this association: "As men age, successive germ cell replications occur, and de novo [new, not passed from parent to offspring] mutations accumulate monotonously as a result of DNA copy errors," they say. "Women are born with their full supply of eggs that have gone through only 23 replications, a number that does not change as they age. Therefore, DNA copy errors should not increase in number with maternal age. Consistent with this notion, we found smaller effects of increased maternal age on the risk of bipolar disorder in the offspring."

Advancing Paternal Age and Bipolar Disorder
Emma M. Frans; Sven Sandin; Abraham Reichenberg; Paul Lichtenstein; Niklas Langstrom; Christina M. Hultman
Arch Gen Psychiatry. 2008;65(9):1034-1040.
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Written by Anna Sophia McKenney
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