TUESDAY September 2, 2008 (foodconsumer.org) – Fathers’ older age may be a risk factor for bipolar disorder in their children, according to a study published in the Sep. 2008 issue of Archives of General Psychiatry.

Bipolar disorder is a severe mood disorder that triggers episodes of mania and depression, according to background information in the article.   The condition affects an estimated 2.3 million Americans, according to the National Institute of Health.

Emma M. Frans, M.Med.Sc., of the Karolinska Institutet, Stockholm, Sweden, and colleagues compared 13,428 patients in Swedish registers with a diagnosis of bipolar disorder with those with sex and age matched, but without the condition to examine the effect of paternal age on the risk of the condition.

The researchers found the older an individual's father, the more likely he or she was to develop bipolar disorder.   A child would have an increased risk if he was born when his father was 29 years old or older.

"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," the authors wrote.

The ages of older mothers also had an effect on the risk, which was not as significant as the ages of older fathers.   There was no association between the mother's age and early bipolar disorder (diagnosed before the age of 20).   But the association existed for the father's age.

The researchers explained that de novo mutations occur in germ cell replications while women's eggs do not have as many replications and mutations may not be as common in eggs. Because of this, maternal age does not affect the risk of bipolar disorder in children as much as the father's age.

Few risk factors have been identified for bipolar disorder.

Older paternal age has been linked in previous studies to higher risk of complex neurodevelopmental disorders, including schizophrenia and autism, according to the press release by JAMA and Archives Journals.