Long-term marijuana smokers who abstain from the drug for one week or more perform no differently on cognition tests than nonusers, according to findings published in the current issue of the Archives of General Psychiatry.
Researchers said that test subjects comprised of long-term daily smokers “showed virtually no significant differences from control subjects (those who had smoked marijuana less than 50 times in their lives) on a battery of 10 neuropsychological tests. Former heavy users, who had consumed little or no cannabis in the three months before testing, [also] showed no significant differences from control subjects on any of these tests on any of the testing days.”
Authors did claim that current heavy smokers tested more poorly than controls for up to seven days after discontinuing the drug on one test measuring “memory of word lists.”
A previous study by researchers at John Hopkins University of the potential effects of long-term pot smoking found “no significant differences in cognitive decline between heavy users, light users, and nonusers of cannabis” over a 15-year period in a cohort of 1,318 subjects.
According to NORML Board Member Dr. John P. Morgan, author of Marijuana Myths, Marijuana Facts: A Review of the Scientific Evidence: “There is no convincing evidence that [even] heavy long-term marijuana use impairs memory or other cognitive functions. … During the past 30 years, researchers have found, at most, minor cognitive differences between chronic marijuana users and nonusers, and the results differ substantially from one study to another.”
Full text of the study may be accessed online at the Archives of General Psychiatry website at: http://archpsyc.ama-assn.org/.
For more information, please contact either Allen St. Pierre or Paul Armentano of The NORML Foundation at (202) 483-8751.
