SAN FRANCISCO – The “medical” use of marijuana, which is common among patients diagnosed with illnesses such as HIV or cancer, might lead to depression or anxiety disorders. However, data suggesting that marijuana use is a risk factor for throat and neck cancers are weak, two experts say.
Evidence that marijuana use might play an etiological role in the development of psychotic disorders and schizophrenia has been mounting (Eur. Arch. Psychiatry Clin. Neurosci. 2009;259:413–31, Am. J. Psychiatr. 2009;166:1251–7). The relationship between marijuana (or “pot”) and anxiety or mood disorders, however, is less clear, Dr. Robert B. Daroff Jr., director of the HIV Psychiatry Program at the San Francisco VA Medical Center, said at a meeting on the medical management of HIV sponsored by the University of California, San Francisco.
Patients with HIV often contend that they are self-medicating to symptoms and that the most common “diagnosis” associated with medical marijuana use is “stress,” he said.
“I usually advise–and this doesn't always go smoothly–that depressed or anxious patients take a trial off of pot before I treat their depression or their anxiety,” he said. If patients are willing to try interrupting marijuana use, often they will find that the drug was a major contributing factor to their psychiatric symptoms.
“At least for patients who have treatment-resistant depression and anxiety, we ought to be pushing harder for them to give a trial off of pot to see if that's related” to their psychiatric problem, he said.
Deborah Greenspan, D.Sc., professor and chair of orofacial sciences and distinguished professor of dentistry at the university, said anecdotal reports that the practice of using marijuana contributes to the development of oral squamous cell carcinoma (SCC) prompted her to review studies related to this topic.
A large, population-based case-control study with 407 subjects found no association between marijuana use and SCC either in the cohort as a whole or in any subgroup based on age, cigarette smoking status, or alcohol consumption (Cancer Research 2004;64:4,049–54).
An analysis of five case-control studies with 4,029 cases of head and neck cancer, and 5,015 control patients found no significant association between cancer and marijuana use in patients who did not smoke cigarettes (Cancer Epidemiol. Biomarkers Prev. 2009;18:1544–51).
“There may have been some dual activity going on” from cigarette use by marijuana smokers that contributed to suggestions that marijuana increased cancer risk in some earlier small studies, Dr. Greenspan said.
Dr. Daroff and Dr. Greenspan reported having no relevant disclosures.