Julie Gardener
New Member
Association between cannabis use and depression may not be causal, study says
Dr. Michael T. Lynskey and colleagues at the Washington University School of Medicine in St. Louis examined the role of genetics and influence of environment during childhood in the relationship between cannabis use and major depression. His team interviewed individuals of the Australian Twin Register, at around 30 years of age.
They identified 277 pairs in which one twin used cannabis while the other didn't. The odds of depression, suicidal thoughts and attempted suicide were 1.3 to 3.4 times more likely in the cannabis-using twin compared with the twin who was not a user. The strength of the association was higher in fraternal twins (dizygotic) than identical twins (monozygotic). This latter finding implies that "genetic vulnerabilities make substantial contributions" to the association between marijuana use and depression, the authors report.
These results suggest that "depression does not cause people to use (cannabis), or that (cannabis) use and dependence do not in themselves cause depression," Lynskey said in an interview with Reuters Health. "So from a clinical point of view, it is not necessarily the case that eliminating one of those will automatically get rid of the other." In other words, he added, both problems "need to be addressed within the treatment setting."
(Sources: Reuters Health of 8 October 2004; Lynskey MT, et al. Major depressive disorder, suicidal ideation, and suicide attempt in twins discordant for cannabis dependence and early-onset cannabis use. Arch Gen Psychiatry 2004;61(10):1026-32.)
Source: International Association for Cannabis as Medicine
Dr. Michael T. Lynskey and colleagues at the Washington University School of Medicine in St. Louis examined the role of genetics and influence of environment during childhood in the relationship between cannabis use and major depression. His team interviewed individuals of the Australian Twin Register, at around 30 years of age.
They identified 277 pairs in which one twin used cannabis while the other didn't. The odds of depression, suicidal thoughts and attempted suicide were 1.3 to 3.4 times more likely in the cannabis-using twin compared with the twin who was not a user. The strength of the association was higher in fraternal twins (dizygotic) than identical twins (monozygotic). This latter finding implies that "genetic vulnerabilities make substantial contributions" to the association between marijuana use and depression, the authors report.
These results suggest that "depression does not cause people to use (cannabis), or that (cannabis) use and dependence do not in themselves cause depression," Lynskey said in an interview with Reuters Health. "So from a clinical point of view, it is not necessarily the case that eliminating one of those will automatically get rid of the other." In other words, he added, both problems "need to be addressed within the treatment setting."
(Sources: Reuters Health of 8 October 2004; Lynskey MT, et al. Major depressive disorder, suicidal ideation, and suicide attempt in twins discordant for cannabis dependence and early-onset cannabis use. Arch Gen Psychiatry 2004;61(10):1026-32.)
Source: International Association for Cannabis as Medicine
