Neuropsychological Consequences of Long-term Substance Abuse
Biological Psychiatry Research Laboratory, McLean Hospital
Harrison G. Pope, Jr., M.D., Deborah Yurgelun-Todd, Ph.D., Amanda J. Gruber, M.D.
The Biological Psychiatry Laboratory is engaged in a series of studies looking at the neuropsychological effects of long-term use of cannabis, hallucinogens, and other drugs of abuse. In the cannabis studies, we are recruiting long-term heavy marijuana users who have typically smoked at least 5000 times in their lives. These individuals are then required to abstain from smoking for 28 days, monitored by daily observed urine samples. Neuropsychological testing, using a battery of paper-and-pencil tests, is conducted at Days 0, 1, 7, and 28 of abstinence. In addition, we are conducting a series of functional magnetic resonance imaging (fMRI) studies of long-term cannabis users and controls to assess for possible functional impairments detectable on imaging, even if these impairments are not detectable with classical paper-and-pencil tests.
In a second series of studies, we are looking at the long-term neuropsychological effects of hallucinogen use. In one study, we are administrating a battery of neuropsychological tests, similar to those used in the cannabis studies described above, to Navajos who are members of the Native American Church, and who have used the hallucinogenic cactus, peyote, as a religious sacrament on a regular basis. Members of the Native American Church represent a unique population, in that they have extensive exposure to a hallucinogen, while using no other drugs or alcohol. Control groups for the study include Navajos with a past history of alcohol dependence and control Navajos with no significant history of alcohol use, peyote use, or use of other substances. In a second hallucinogen study, we are investigating the phenomenon of "flashbacks" reportedly associated with hallucinogenic drugs. We are currently reviewing the literature in this area, and will be conducting interviews of individuals who report this phenomenon, in order to develop a better understanding of the phenomenology of "flashbacks," and better operational criteria to diagnose them.
In a third projected series of studies, we will be looking at long-term users of MDMA ("ecstasy") selected because they have used virtually no other drugs, including alcohol. These subjects will be compared, again using similar batteries of neuropsychological tests, against matched controls.
Key words: marijuana, ecstasy, hallucinogens, peyote, neuropsychological
Grant Support: NIDA MERIT Award Cognitive Consequences of Long-Term Marijuana Use - R37 DA10346
Program Site: Biological Psychiatry Laboratory, Oaks Building, McLean Hospital
Program Director: Harrison G. Pope, Jr., M.D., McLean Hospital, 115 Mill Street, Belmont, MA 02478; email address: pope@mclean.harvard.edu
Contact Person: Frances Nestor, Administrative Assistant, (617) 855-2911; Fax: (617) 855-3585
Training Opportunities: None
Representative Publications:
Pope HG Jr, Yurgelun-Todd D. The residual cognitive effects of heavy marijuana use in college students. JAMA 1996;275:521-7.
Pope HG Jr, Jacobs A, Mialet J-P, Yurgelun-Todd D, Gruber S. Evidence for a sex-specific residual effect of cannabis on visuospatial memory. Psychother Psychosom 1997;66:179-84.
Halpern JH, Pope HG Jr. Do hallucinogens cause residual neuropsychological toxicity? Drug Alcohol Depend 1999;53:247-56.
Klitzman RL, Pope HG Jr, Hudson JI. MDMA (ecstasy") abuse and high-risk sexual behaviors among 169 gay men and bisexual men. Am J Psychiatry 2000;157:1162-4.
Halpern JH, Pope HG Jr. Hallucinogens on the internet: a vast new source of "underground"drug information. Am J Psychiatry 2001;158:481-3.
Pope HG Jr, Gruber AJ, Hudson JI, Huestis MA, Yurgelun-Todd, D. Neuropsychological performance in long-term cannabis users. Arch Gen Psychiatry 2001;58:909-15.