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Mortality risk higher among early, heavy cannabis users

Individuals with an early history of heavy cannabis use have higher risk for death than those with no history of cannabis use, according to recent findings.

“Cannabis abuse is associated with adverse effects on aspects of adolescent mental health, including cognitive and psychosocial functioning. Also, cannabis smoke has many elements in common with tobacco smoke, and effects in relation to cancer, cardiovascular disease, and pulmonary disease have been documented,” Edison Manrique-Garcia, MD, PhD, of Karolinska Institutet, Stockholm, and colleagues wrote. “Although these medical conditions are in turn associated with excess mortality in the general population, a systematic review by Calabria et al did not find sufficient evidence to conclude that the all-cause mortality of cannabis users is increased compared with that of nonusers.”

Edison Manrique-Garcia

To assess associations between cannabis use, psychosis and mortality, researchers evaluated 50,373 Swedish male military conscripts, aged 18 to 19 years, who were followed in the National Cause of Death Register up to age 60 years.

Risk for death was significantly higher among study participants with a baseline history of heavy cannabis use (HR = 1.4; 95% CI, 1.1-1.8) than those without such a history.

Researchers found higher mortality among participants with psychotic disorders, though rates did not differ between those with a history of cannabis use ever (HR = 3.8; 95% CI, 2.8-5) or heavy use (HR = 3.8; 95% CI, 2.6-6.2), compared with those without a history of use (HR = 3.7; 95% CI, 3.1-4.4).

There was no association between cannabis use and diagnosis of psychotic disorders regarding mortality, according to researchers.

“Study limitations notwithstanding, we found that subjects with a baseline history of heavy use of cannabis have an increased risk of death over the course of follow-up. We did not find that a history of cannabis use affects the excess mortality among subjects with psychotic disorders, and we did not find an interaction effect between cannabis use and diagnosis of psychotic disorders with regard to mortality,” the researchers concluded. – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.