Study: Marijuana Smoking Linked With Short-Term Clinical Benefits In Patients With Bipolar Disorder

Boston, MA: Cannabis inhalation is associated with the alleviation of clinical symptoms in patients with bipolar disorder (BP), according to clinical findings published in the open-access journal PLoS ONE.

Investigators at Harvard Medical School and McLean Hospital in Boston assessed the effects of cannabis inhalation on mood and neuropsychological performance in patients with BP over a period of several weeks.

Researchers reported that bipolar patients experienced decreased levels of various clinical symptoms – including depression, mania, anger, and anxiety – after inhaling cannabis. Although marijuana-using subjects did perform more poorly on certain cognitive tests compared to healthy controls, these subjects performed no differently than did comparable BP patients with no history of cannabis use.

Authors concluded: “[D]irect analyses of the marijuana-smoking BP patients before and after marijuana use revealed notable symptom alleviation within four hours of smoking, [such as] …. significantly lower scores of anger, tension, [and] depression, as well as higher levels of vigor. … With regard to cognitive performance, marijuana smokers and BP patients performed more poorly than healthy controls overall. However, within the BP patients, impairment was observed regardless of marijuana use status. … Taken together, study findings suggest that marijuana use may result in at least short-term mood term stabilization for a subset of BP patients, and further, that marijuana use does not have an additive, negative impact on cognitive performance in BP patients.”

The study is the first clinical trial to examine the effects of cannabis on both mood and cognitive performance in BP patients.

Bipolar disorder is estimated to affect some 5.7 million American adults.

For more information, please contact Paul Armentano, NORML Deputy Director, at: Full text of the study, “A pilot investigation of the impact of bipolar disorder and marijuana use on cognitive function and mood,” appears online in PLoS ONE.