Older fathers more likely to have children with bipolar disorder

According to new research by Swedish scientists, older fathers are more likely to have children with bipolar disorder.

The researchers suggest the risk goes up when men are older than 29 before they start their family, and is highest if they are over 55 as their sperm is more likely to carry genetic errors.

Other research has already linked increased paternal age with schizophrenia and autism, but not with bipolar disorder.

The researchers say men make new sperm throughout their adult life unlike women who are born with all their eggs and the process of making sperm involves copying DNA, and this is subject to error, particularly as men age.

The researchers from the Karolinska Institute say as women are born with their full supply of eggs, DNA copy errors should not increase in number with maternal age.

Bipolar disorder appears to run in families, so the research team identified 13,428 patients in Swedish registers with a diagnosis of bipolar disorder and for each one, they randomly selected from the registers, five controls who were the same sex and born the same year but did not have bipolar disorder.

When factors such as age of the individual's mother, number of siblings, socioeconomic status and family history of mental health problems, were considered, a clear link between risk of bipolar disorder and father's age was seen and the older an individual's father, the more likely he or she was to have bipolar disorder.

The team led by Dr. Emma M. Frans, found the children of men 55 years and older were 1.37 times more likely to go on to be diagnosed with bipolar disorder than those of men aged 20 to 24.

The exact causes of bipolar disorder, which affects 1 in every 100 people in their lifetime, remains unclear.

People with bipolar disorder swing between intense depression and mania which are interspersed with periods of relative calm.

Bipolar disorder is a complex and severe mood disorder and is a debilitating condition which takes its toll on sufferers and their families and friends.

It affects all aspects of the lives of victims and places them at an increased risk for suicide and other than a family history of psychotic disorders, few risk factors for the condition have been identified.

The research appears in the September issue of Archives of General Psychiatry, one of the JAMA/Archives journals.