It's well known that cigarettes are bad for your health, but does smoking make you more likely to kill yourself too?
In a paper published Wednesday in the journal Nicotine & Tobacco Research, authors argued that smoking and suicide may be more closely related than previously thought.
The researchers analyzed suicide rates in states that aggressively implemented anti-smoking policies from 1990 to 2004 and compared them to suicide rates in states that had more relaxed policies.
Those states that imposed cigarette excise taxes and smoke-free air regulations had lower adjusted suicide rates than did states with fewer anti-smoking initiatives, authors wrote.
"There does seem to be a substantial reduction in the risk for suicide after these policies are implemented," said lead study author Richard Grucza, a psychiatric epidemiologist at Washington University School of Medicine in St. Louis.
"For every dollar in excise taxes there was actually a 10% decrease in the relative risk for suicide," Grucza told Washington University BioMed Radio. "The smoke-free air policies were also very strongly associated with reduced suicide risk."
Study authors said that states with lower taxes on cigarettes and more lax policies on public smoking had suicide rates that were up to 6% greater than the national average.
This is not the first study to document a correlation between cigarette smoking and suicide, but it is among the first to suggest smoking and nicotine may be specific factors.
Up until now, researchers believed smoking coincided with suicide because people with psychiatric problems or substance abuse problems were more likely to smoke as well as to commit suicide.
"Markedly elevated rates of smoking are found among people with anxiety disorders, alcohol and drug dependence, schizophrenia and other diagnoses, in both clinical and general studies," authors wrote. "However, it is also possible that smoking is not merely a marker for psychiatric disorders, but rather directly increases the risk for such disorders, which in turn increases the risk for suicide."
Grucza said that the imposition of anti-smoking rules presented the researchers with a naturally occurring experiment. However, the authors did note that there were limitations on their research.
In particular, they said that since they considered state-imposed anti-smoking efforts only, their research would not account for local-level policies aimed at smoking behavior.
"While further studies may be required to establish a compelling weight of evidence, this study provides strong epidemiological support in its favor of the proposition that smoking is a casual risk factor for suicide," authors wrote.