Aside from being the leading cause of lung cancer, smoking may also increase the risk of suicide.
On studying a group of young people, it was found that regular smokers had a greater risk of suicidal thoughts or attempts, even without a prior history of depression or addiction. Such a link was not seen in those who had quit smoking.
Although the reason for this is not clear, it is suggested that the observed effects of smoking on serotonin levels in the brain may be involved .