“How to manage medical complications of the 5 most abused substances” (Current Psychiatry, November 2009, p. 35-47) contains several errors of fact, emphasis, and inappropriate citation of references that may mislead readers.
The article states “marijuana use can double or triple the risk of cancer of the respiratory tract and lungs” and cites a reference by Tashkin et al.1 In fact, that review article states “…evidence that marijuana smoking may lead to…respiratory cancer is limited and inconsistent.” A subsequent case-control study by Tashkin and colleagues found no increased risk of lung or upper respiratory tract cancer among heavy marijuana smokers.2 A smaller case-control study from New Zealand did find an 8% increased risk of lung cancer associated with each joint-year of marijuana smoking.3 However, the Current Psychiatry article grossly exaggerated the cancer risk from marijuana smoking and cited an inappropriate supporting reference.
The article states that “growing evidence shows that marijuana use could lead to cardiac arrhythmias, such as atrial fibrillation” and cites 1 supporting reference.4 That article reviewed the 6 published cases of atrial fibrillation (AF) associated with marijuana smoking and acknowledged “the exact incidence of AF related to marijuana smoking is difficult to be estimated.” Other reviews of the cardiovascular effects of marijuana smoking take a broader view, eg, “marijuana’s cardiovascular effects are not associated with serious health problems for most young, healthy users.”5 Given the ratio between 6 published case reports and the millions of people smoking marijuana daily, this may be a more appropriate perspective for a review article.
The article states “some studies show persistent cognitive impairments in longer term cannabis users, even after 2 years of abstinence” and cites 1 supporting reference by Pope et al6 (incorrectly cited as Harrison et al). In fact, that study did not test subjects beyond 28 days of abstinence; at the time, “the differences between users and controls had narrowed and were mostly nonsignificant.” Other studies have found no significant differences between marijuana smokers and non-users after 3 months of abstinence,7 nor are significant long-term cognitive deficits mentioned in recent reviews of the topic.8 Thus, we are not aware of any scientific basis for the statement in the article, which is not supported by the 1 study cited.
The paragraph on “cardiac complications” of cocaine use presents an incomplete picture of the risk of myocardial infarction (MI) and cites only 1 (2001) review article. What would have been useful to the reader was:
- cocaine-associated MI occurs in up to 6% of patients with cocaine-associated chest pain9
- cocaine-associated MI may have atypical symptomatic presentation, eg, without chest pain9
- in a large, population-based study, adults age 18 to 45 who used cocaine >10 times had a 3.5-fold increased risk of MI10
- two-thirds of MIs occur within 3 hours of cocaine ingestion, but MI may occur >18 hours after ingestion (possibly due to pharmacologically active cocaine metabolites).9 The recent review by McCord et al,9 which includes treatment recommendations from the American Heart Association, would have been useful to cite.
Most readers of Current Psychiatry are not specialists in the topics covered by its review articles. This places increased responsibility for ensuring accurate and balanced topic coverage with citation of appropriate, up-to-date review articles.
David A. Gorelick, MD, PhD
National Institute on Drug Abuse
Baltimore, MD
References
1. Tashkin DP. Smoked marijuana as a cause of lung injury. Monaldi Arch Chest Dis. 2005;63(2):93-100.
2. Hashibe M, Morgenstern H, Cui Y, et al. Marijuana use and the risk of lung and upper aerodigestive tract cancers: results of a population-based case-control study. Cancer Epidemiol Biomarkers Prev. 2006;15(10):1829-1834.
3. Aldington S, Harwood M, Cox B, et al. Cannabis use and risk of lung cancer: a case-control study. Eur Respir J. 2008;31(2):280-286.
4. Korantzopoulos P, Liu T, Papaioannides D, et al. Atrial fibrillation and marijuana smoking. Int J Clin Pract. 2008;62(2):308-313.
5. Jones RT. Cardiovascular system effects of marijuana. J Clin Pharmacol. 2002;42(11 suppl):58S-63S.
6. Pope HG, Jr, Gruber AJ, Hudson JI, et al. Cognitive measures in long-term cannabis users. J Clin Pharmacol. 2002;42(11 suppl):41S-47S.
7. Fried PA, Watkinson B, Gray R. Neurocognitive consequences of marihuana—a comparison with pre-drug performance. Neurotoxicol Teratol. 2005;27(2):231-239.
8. Schweinsburg AD, Brown SA, Tapert SF. The influence of marijuana use on neurocognitive functioning in adolescents. Curr Drug Abuse Rev. 2008;1(1):99-111.
9. McCord J, Jneid H, Hollander JE, et al. Management of cocaine-associated chest pain and myocardial infarction: a scientific statement from the American Heart Association Acute Cardiac Care Committee of the Council on Clinical Cardiology. Circulation. 2008;117(14):1897-1907.
10. Aslibekyan S, Levitan EB, Mittleman MA. Prevalent cocaine use and myocardial infarction. Am J Cardiol. 2008;102(8):966-969.