Middle-aged and elderly men who smoke heavily were more likely to commit suicide, a major survey by Japan's Ministry of Health, Labor and Welfare found.

An epidemiological survey conducted by a research team at the ministry found that the rate of suicide among middle-aged and elderly men was linked to the number of cigarettes they smoked.

Japanese researchers studied the relationship between smoking habits and 173 men aged between 40 and 69 committed suicide during the period.

A total of 108 of the 173 people who committed suicide were smokers. The rate of suicide among people who smoked less than 20 cigarettes per day was about the same as for nonsmokers, but the suicide rate of people who smoked between 30 and 39 cigarettes per day was 1.4 times higher than those in the group who smoked under 20 cigarettes a day.

The rate of suicide for those who smoked 40 or more cigarettes a day was 1.7 times higher. Researchers said no differences were seen based on the number of years people had been smoking.

A separate autopsy survey conducted by Kochi University last year found that among people who smoked, there was a higher concentration of nicotine in the blood of people who committed suicide than among those who died in accidents or because of illness.

Motoki Iwasaki, a scientist at the Epidemiology and Prevention Division of Japan's National Cancer Center, said nicotine dependency was believed to increase the risk of depression.

"The mechanism connecting smoking to suicide is not well understood, but there are research results showing that dependency on nicotine increases the risk of depression," he said.

Source: China Daily