title: Abstinent adolescent marijuana users show altered fMRI response during spatial working memory.
abstract: Marijuana is the most widely used illicit substance among teenagers, yet little is known about the possible neural influence of heavy marijuana use during adolescence. We previously demonstrated an altered functional magnetic resonance imaging (fMRI) activity related to spatial working memory (SWM) among adolescents who were heavy users of after an average of 8 days of abstinence, but the persisting neural effects remain unclear. To characterize the potentially persisting neurocognitive effects of heavy marijuana use in adolescence, we examined fMRI response during SWM among abstinent marijuana-using teens. Participants were 15 MJ teens and 17 demographically similar non-using controls, ages 16-18. Teens underwent biweekly urine toxicology screens to ensure abstinence for 28 days before fMRI acquisition. Groups performed similarly on the SWM task, but MJ teens demonstrated lower activity in right dorsolateral prefrontal and occipital cortices, yet significantly more activation in right posterior parietal cortex. MJ teens showed abnormalities in brain response during a SWM task compared with controls, even after 1 month of abstinence. The activation pattern among MJ teens may reflect different patterns of utilization of spatial rehearsal and attention strategies, and could indicate altered neurodevelopment or persisting abnormalities associated with heavy marijuana use in adolescence.
authors: University of California San Diego, Department of Psychology, 9500 Gilman Dr., 0109, La Jolla, CA 92093-0109, USA.
authors: Alecia D
authors: AD
authors: Schweinsburg
authors: Bonnie J
authors: BJ
authors: Nagel
authors: Brian C
authors: BC
authors: Schweinsburg
authors: Ann
authors: A
authors: Park
authors: Rebecca J
authors: RJ
authors: Theilmann
authors: Susan F
authors: SF
authors: Tapert
mesh_terms: D000293:Adolescent; D001931:Brain Mapping; D002186:Cannabinoids / Q000633:toxicity*; D002540:Cerebral Cortex / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D002189:Marijuana Abuse / Q000503:physiopathology* / Q000534:rehabilitation*; D008570:Memory, Short-Term / Q000187:drug effects* / Q000502:physiology; D009778:Occipital Lobe / Q000187:drug effects / Q000503:physiopathology; D009949:Orientation / Q000187:drug effects* / Q000502:physiology; D010296:Parietal Lobe / Q000187:drug effects / Q000503:physiopathology; D010364:Pattern Recognition, Visual / Q000187:drug effects* / Q000502:physiology; D017397:Prefrontal Cortex / Q000187:drug effects / Q000503:physiopathology; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012016:Reference Values; D013375:Substance Withdrawal Syndrome / Q000503:physiopathology*
chemical_list: D002186:Cannabinoids