Cannabis abuse and serious suicide attempts

Aims. To compare the relationship between cannabis abuse/dependence and ris k of medically serious suicide attempts in individuals making serious suici de attempts and randomly selected comparison subjects. Design. Case-control comparison. Setting. Cases, a general hospital; controls, the local commun ity. Participants. Cases were 302 consecutive individuals making medically serious suicide attempts; 1028 randomly selected control subjects. Measurem ents. DSM-III-R mental disorder diagnoses; measures of socio-demographic ch aracteristics and childhood and family experiences. Findings, Of those maki ng serious suicide attempts, 16.2% met DSM-III-R criteria for cannabis abus e/dependence at the time of the attempt, compared with 1.9% of comparison s ubjects (OR = 10.3; 95% CI, 5.95-17.8, p < 0.0001). Risks of serious suicid e attempt were significantly related to a series of socio-demographic and c hildhood characteristics, and to mental disorders that were co-morbid with cannabis abuse/dependence. When the association between cannabis abuse/depe ndence and suicide attempt risk was controlled for socio-demographic factor s, childhood factors and concurrent psychiatric morbidity, there was a marg inally significant association (OR = 2.0; 95% CI, 0.97-5.3, p < 0.06) betwe en cannabis abuse/dependence and serious suicide attempt risk. Conclusions. These results suggested that much of the association between cannabis abus e/dependence and suicide attempt risk arose because: (a) individuals who de velop cannabis abuse/dependency tend to come from disadvantaged socio-demog raphic and childhood backgrounds which, independently of cannabis abuse, ar e associated with higher risk of suicide attempt, or (b) because cannabis a buse/dependence is co-morbid with other mental disorders which are independ ently associated with suicidal behaviour. Nevertheless, the possibility rem ains that cannabis abuse/dependence may make an independent contribution to risk of serious suicide attempt, both directly and through the possible ef fects of cannabis abuse on risk of other mental disorders.