Offspring of Older Men at Greater Risk for Bipolar Disorder

Men over the age of 30 who father children increase the risk for their offspring to develop bipolar disorder, commonly called manic depression. In addition, the risk for the condition increases with the age of a father, up to 37 percent when a new father reaches the age of 55.
Bipolar disorder is a brain disorder that causes a fluctuation between intense depression and mania, including extreme shifts in mood, energy and ability to function with periods of relative calm in between. It is characterized by high periods of elation or irritability and low periods of sadness and hopelessness that can last as long as months. About 1 in every 100 people will develop bipolar disorder in their lifetime. The exact causes the condition are not known, but it seems to run in families.
The findings of the study support evidence that children of older fathers share an increased risk of psychological conditions including bipolar disorder, autism and schizophrenia. The theory behind this evidence is based on the genetics of aging sperm. As a man ages, spontaneous mutations can accumulate in the genes of his sperm cells. By some estimates, the cells can divide as many as 660 times by the time a man reaches age 40. With each division comes an increased risk of acquiring a harmful mutation from erroneous gene copying.
This risk does not include women. Unlike men, who make new sperm throughout their adult life, women are born with all their eggs. DNA copy errors don't increase in number with maternal age. However, women do have a higher risk of giving birth to a child with Down syndrome as they become older.
Emma Frans, an epidemiologist at the Karolinska Institute in Sweden, led the Swedish research team. During the study, the group identified 13,428 men and women who had been diagnosed with bipolar disorder by using a national medical registry. For each one of these people, five control subjects of the same sex and age who did not have the condition were randomly selected. Once they factored in maternal age, the group found that children born to fathers older than 30 years of age had an 11 percent greater risk of developing bipolar disorder when compared to children of younger fathers and children with fathers older than 55 had a 37 percent greater risk. The researchers also accounted for education level, age of the mother, family history of psychotic disorders and the number of children the mother had.
In a telephone interview, Frans noted that the findings do not mean that older men should not become fathers, as the overall risk is still low. She said, "The study sheds light on the negative effect of older fathers but most older men will still have healthy children."
The findings of the study are published in the Archives of General Psychiatry.