Decreased Dopamine Brain Reactivity in Marijuana Abusers Is Associated
Decreased dopamine brain reactivity in marijuana PNAS PLUS abusers is associated with negative emotionality and addiction severity Nora D. Volkowa,b,1, Gene-Jack Wanga, Frank Telanga, Joanna S. Fowlerc,1, David Alexoffc, Jean Logand, Millard Jaynea, Christopher Wonga, and Dardo Tomasia aLaboratory of Neuroimaging, National Institute on Alcohol Abuse and Alcoholism, Rockville, MD 20857; bNational Institute on Drug Abuse, Rockville, MD 20857; cBiosciences Department, Brookhaven National Laboratory, Upton, NY 11973; and dDepartment of Radiology, New York University Langone Medical Center, New York, NY 10016 Contributed by Joanna S. Fowler, June 20, 2014 (sent for review April 9, 2014; reviewed by Bertha Madras, Harvard University Medical School, and Karen Berman, National Institute of Mental Health) Moves to legalize marijuana highlight the urgency to investigate ref. 6). Similarly, cocaine abusers (17, 18) and alcoholics (19, 20), effects of chronic marijuana in the human brain. Here, we chal- but not marijuana abusers (16), show attenuated DA increases in lenged 48 participants (24 controls and 24 marijuana abusers) with striatum when challenged with a stimulant drug, although mar- methylphenidate (MP), a drug that elevates extracellular dopamine ijuana abusers with comorbid schizophrenia or risk for schizo- (DA) as a surrogate for probing the reactivity of the brain to DA phrenia showed blunted DA increases to stimulants (21) and to stimulation. We compared the subjective, cardiovascular, and brain stress (22). However, prior studies are limited by their small DA responses (measured with PET and [11C]raclopride) to MP be- sample sizes (ranging from six to 16 subjects). Also, prior studies tween controls and marijuana abusers.
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