Since earlier researches have found a link between older paternal age and risk for autism and schizophrenia, Swedish scientists decided to check the role of paternal age in bipolar disorder. They find that children born from older fathers are at increased risk of developing bipolar disorder too.

The risk of developing bipolar was found to be 2.5-times greater for children born to men age 50 and older than for children born to men between the ages of 20 and 24. Although the increase in risk was quite strong, on the individual level, it is still relatively small since only few men have been having children at this age so far.

Not much is known about the causes of bipolar disorders but the numbers of sufferers are quite clear. Only in the United States, 5.7 million adults suffer from this serious mental illness characterized by dramatic, episodic mood swings.

There is a known genetic tendency but little else is known about the causes of bipolar disorder.

In their study, the Swedish scientists have identified around 13,500 people with f bipolar disorder and matched them to people without the disorder who were the same sex and born in the same year for comparison.

Maternal age and several other potential influences on the risk have been taken into account. The study results showed that children born to men 55 years of age and older were 1.37 times more likely to have a diagnosis of bipolar disorder than the children born to men between the ages of 20 and 24. Maternal age played no significant role in the disorder.
Researchers believe it is mutations in sperm of older men that could be blamed. Male reproductive cells continue to divide throughout their lives and more divisions mean more possible mutations and DNA damage that could be possibly increasing the risk of bipolar and other mental disorders.

This area of research is relatively knew and the researchers are just beginning to understand the impact of paternal age on children's health. It is important to find the potential risks since many more men are having children later in life.