Teen male smokers at high risk for future suicide

NEW YORK (Reuters Health) - Boys who are regular smokers by age 14 are four times as likely as their peers who haven't picked up the habit to kill themselves before they reach age 34, Finnish researchers report.

"We consider our findings important, since as many as one in five adolescents in the Finnish general population are known to be smokers at the age of 14 years today," Dr. Kaisa Riala of Oulu University Hospital and her colleagues write.

While the link between smoking and increased suicide risk is well known, Riala and her team point out in the Journal of Clinical Psychiatry, smoking during adolescence and later suicide risk has not been studied.

To investigate, Riala and her team analyzed information from 10,934 individuals born in Finland in 1966. Using data reported to the Finnish Hospital Discharge Register, they linked suicide attempts by the end of 2001 to data on smoking at age 14, which was obtained by questionnaires.

Among the 5034 males in the study, 2.6 percent of the regular, daily smokers at age 14 had killed themselves by age 34, compared with 0.8 percent of those who experimented with smoking and 0.4 percent of those who didn't smoke at all, the researchers found.

When the researchers accounted for other factors linked to suicide risk, as well as psychiatric problems, they found that males who were regular smokers in adolescence still had a 4.05-fold increased risk of suicide.

No link between smoking at a young age and suicide risk was seen among females. However, girls who were regular daily smokers were more likely to attempt suicide; 4.2 percent had tried to kill themselves, compared with just 1.2 percent of their peers.

Among males, 3.3 percent of regular smokers had attempted suicide, compared with 1.2 percent of those who weren't regular smokers.

Smoking is known to be a risk factor for the development of depression, the researchers note, but the smoking-depression link does not explain the gender difference identified in the current study.

They point out that cigarette smoking has been shown to lower serotonin levels, and reduced amounts of this brain chemical have been tied to both depression and aggression. Testosterone levels also are higher in smokers, the researchers add, which could play a role in the smoking-suicide link.

"Further studies are needed to investigate the effects of smoking on the neurobiology of depression, self-damaging aggression, and impulsivity," the researchers conclude.

SOURCE: Journal of Clinical Psychiatry May 2007.