A new study has revealed that older fathers are likely to have children with psychiatric problems and the risk is much more than what was previously thought. Bipolar disorder, autism and attention deficit are some of the mental problems that are likely to be found in children having older dads.

The study saw examination of data on more than 2.6 million Swedes born from 1973-2001. The American and Swedish researchers found that men who became father after the age of 24 were more likely to have children with psychiatric problems or academic difficulties. The risk further increased at the age of 45 and above.

The findings have debunked the belief that men's sperms are timeless but the study no way makes it certain that men who father kids at older age always greatly pose the risk of mental disorders on their children. Less than 1% of kids of older dads had autism, attention deficit-hyperactivity disorder or bipolar disorder. Also, less than 4% children having older dads had schizophrenia or died after attempting suicide.

But it was surprising to see the magnitude of increased risk among children born to dads aged 45 and older compared to dads aged 20 to 24, said lead author Brian D'Onofrio, an associate professor in the psychological and brain sciences department at Indiana University.

The risk was almost 25 times greater to develop bipolar disorder for children born to men at age 45 and older compared to those born to youngest dads. The risk among children born to fathers aged 45 and older was 13 times higher for ADHD, more than three times for autism, nearly three times greater for suicide attempts, and about two times higher for schizophrenia than kids born to young fathers.

Molecular geneticist Simon Gregory, an associate professor at Duke University, said, "There's no reason to ring the alarm bells that older men shouldn't have kids" unless the results are replicated in additional research and molecular evidence is found".