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BRIEF COMMUNICATIONS: Lambros Messinis, Anthoula Kyprianidou, Sonia Malefaki, and Panagiotis Papathanasopoulos Neuropsychological deficits in long-term frequent cannabis users Neurology 2006; 66: 737-739 [Abstract] [Full text] [PDF]

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Neuropsychological deficits in long-term frequent cannabis users

Michael Accordino, Carl L. Hart   (15 May 2006)

Reply from the Authors

Lambros Messinis, Papathanasopoulos Panagiotis   (15 May 2006)

Neuropsychological deficits in long-term frequent cannabis users 15 May 2006
Michael Accordino, Columbia University 1051 Riverside Drive, Box #120 New York, NY 10032, Carl L. Hart Send Correspondence to journal: Re: Neuropsychological deficits in long-term frequent cannabis users clh42{at}columbia.edu Michael Accordino, et al.	Dr. Messinis et al [1] concluded that "heavy long-term frequent cannabis use leads to subtle deficits in specific neuropsychological domains." In the Introduction, the authors note that Pope et al [2] did not observe consistent cognitive deficits in frequent long-term cannabis users who had undergone a 28-day abstinence period. However, Messinis et al failed to control for length of abstinent period in their study. It is important to control for this variable because frequent cannabis use is associated with an abstinence syndrome upon cessation of drug use [3], and poor neurocognitive functioning [4] is a key feature of this syndrome. On average, the cannabis users in the Messinis et al study were abstinent for approximately 123 hrs prior to neuropsychological evaluation. Note that the peak effects of the cannabis abstinence syndrome occur between 48 -144 hrs following the cessation of cannabis use. [5] It is likely that study participants in the Messinis et al study were in the midst of cannabis withdrawal during neurocognitive testing. Therefore, the data from this study should be interpreted within the context of this important caveat. References 1. Messinis L, Kyprianidou A, Malefaki S, Papathanasopoulos P. Neuropsychological deficits in long-term frequent cannabis users. Neurology 2006; 66: 737-739. 2. Pope HG, Gruber AJ, Hudson JI, Huestis MA, Todd DY. Neuropsychological performance in long-term cannabis users. Arch Gen Psychiatry 2001; 58: 909–915. 3. Hart CL. Increasing treatment options for cannabis dependence: a review of potential pharmacotherapies. Drug and Alcohol Dependence 2005; 80: 147-159. 4. Haney M, Hart CL, Vosburg SK, et al. Marijuana withdrawal in humans: effects of oral THC or divalproex. Neuropsychopharmacology 2004; 29: 158-170. 5. Budney AJ, Hughes JR, Moore BA, Vandrey R. Review of the validity and significance of cannabis withdrawal syndrome. American Journal of Psychiatry 2004; 161: 1967-1977. Disclosure: The authors report no conflicts of interest.
Reply from the Authors 15 May 2006
Lambros Messinis, Department of Neurology, University of Patras Medical School Rixinoros 6 , Patras , Greece, Papathanasopoulos Panagiotis Send Correspondence to journal: Re: Reply from the Authors lambros{at}hellasnet.gr Lambros Messinis, et al.	We thank Drs. Accordino and Hart for their interest in our study. They raise an important issue concerning the abstinence syndrome upon cessation of cannabis use. Regarding this issue, at the time of neuropsychological assessment, approximately 80% of our sample reported that they were not experiencing any discomfort due to cannabis abstinence and we did not observe any significant withdrawal symptoms in our cannabis groups during testing. A well controlled study by Solowij et al. [6] of long vs. short term cannabis users showed that cognitive impairments (after a median 17-hour abstinence period) were “generally unrelated to withdrawal effects and recent use. Bolla et al [7] reported “persistent decrements in neurocognitive performance even after 28 days of abstinence in heavy cannabis users. Controlled laboratory studies [8, 9] have also shown recent cannabis use to be a minimal confounder in experienced cannabis users, as were the cannabis users in our study. References 6. Solowij, Í, Stephens, RS, Roffman, RA et al. Cognitive functioning of 1ong-term heavy cannabis users seeking treatment. Journal of the American Medical Association. 2002; 287: 1123-1131. 7. Bolla, KI, Brown, K, Eldreth, D et al. Dose-related neurocognitive effects of marijuana use. Neurology. 2002; 59: 1337-1343 8. Hart CL, van Gorp W, Haney M, et al. Effects of acute smoked marijuana on complex cognitive performance. Neuropsychopharmacology. 2001; 25: 757-765. 9. Chait LD. Subjective and behavioural effects of marijuana the morning after smoking. Psychopharmacology (Berl). 1990; 100: 328-333. Disclosure: The authors report no conflicts of interest.