Lithium reduces risk of suicide among people with mood disorders by as much as 60 percent when compared to placebo, a new study has found.

In the U.S., mood disorders affect about one in ten people aged 18 years and above and are a leading cause of disability in the country.

People with mood disorders such as depression and bipolar disorder are 30 times more likely to commit suicide. These people are often treated with lithium that keeps their moods in check. However, whether lithium prevents suicide among these people isn't known.

The present study was conducted by researchers at universities of Oxford, UK and Verona, Italy. The researchers reviewed around 48 randomized controlled trials with a combined sample size of over 6,600 people. In the trials, people were either given lithium with either another psychoactive drug or lithium.

Researchers found that lithium was better than placebo in all trials in reducing risk of suicide, but not self-harm.

Also, only carbamazepine was better than lithium in treating mood disorders in people who were given an active treatment for their condition. Researchers found that overall lithium was a better treatment for people who were at a high risk of committing suicide.

"This updated systematic review reinforces lithium as an effective agent to reduce the risk of suicide in people with mood disorders," the authors said.

A related study had shown that traces of lithium in drinking water could cut the risk of suicide in general population.

According to the researchers lithium may cut the chance of suicide by preventing the person from developing mood disorders again. Also, lithium prevents people from becoming aggressive or impulsive, which could be another possible explanation for lithium's anti-suicidal effect.

The scientists added that lithium isn't entirely safe and has some side-effects. "Understanding the mechanism by which lithium acts to decrease suicidal behavior could lead to a better understanding of the neurobiology of suicide," they concluded.

The study is published in the British Medical Journal.