Major Depressive Disorder, Suicidal Ideation, and Suicide Attempt in Twins Discordant for Cannabis Dependence and Early-onset Cannabis Use

This study examined whether associations between both lifetime cannabis dependence & early cannibus use & measures of major depressive disorder, suicidal ideation & suicide attempt persist after controlling for genetic &/or shared environmental influences. 277 same-sex twin pairs were studied. Individuals who were cannabis dependent had odds of suicidal ideation & suicide attempt that were 2.5-2.9 times higher than those of their non-cannabis dependent twin. Those who started using cannabis before age 17 had elevated rates of suicide attempt but not major depressive disorder or suicide ideation. (39 refs.)