title: Effects of cannabis on impulsivity: a systematic review of neuroimaging findings.
abstract: We conducted a systematic review to assess the evidence for specific effects of cannabis on impulsivity, disinhibition and motor control. The review had a specific focus on neuroimaging findings associated with acute and chronic use of the drug and covers literature published up until May 2012. Seventeen studies were identified, of which 13 met the inclusion criteria; three studies investigated acute effects of cannabis (1 fMRI, 2 PET), while six studies investigated non-acute functional effects (4 fMRI, 2 PET), and four studies investigated structural alterations. Functional imaging studies of impulsivity studies suggest that prefrontal blood flow is lower in chronic cannabis users than in controls. Studies of acute administration of THC or marijuana report increased brain metabolism in several brain regions during impulsivity tasks. Structural imaging studies of cannabis users found differences in reduced prefrontal volumes and white matter integrity that might mediate the abnormal impulsivity and mood observed in marijuana users. To address the question whether impulsivity as a trait precedes cannabis consumption or whether cannabis aggravates impulsivity and discontinuation of usage more longitudinal study designs are warranted.
authors.forename: Johannes
authors.initials: J
authors.lastname: Wrege
authors.forename: Andre
authors.initials: A
authors.lastname: Schmidt
authors.forename: Anna
authors.initials: A
authors.lastname: Walter
authors.forename: Renata
authors.initials: R
authors.lastname: Smieskova
authors.forename: Kerstin
authors.initials: K
authors.lastname: Bendfeldt
authors.forename: Ernst-Wilhelm
authors.initials: EW
authors.lastname: Radue
authors.forename: Undine E
authors.initials: UE
authors.lastname: Lang
authors.affiliation: Department of Psychiatry UPK, University of Basel, Petersgraben 4, 4031 Basel, Switzerland. Stefan.Borgwardt@uhbs.ch.
authors.forename: Stefan
authors.initials: S
authors.lastname: Borgwardt
mesh_terms: D000818:Animals; D001288:Attention / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000473:pathology / Q000502:physiology; D002188:Cannabis / Q000633:toxicity*; D006801:Humans; D007175:Impulsive Behavior / Q000187:drug effects*; D008279:Magnetic Resonance Imaging; D059906:Neuroimaging / Q000379:methods*