Effects of frequent cannabis use on hippocampal activity during an associative memory task.
Interest is growing in the neurotoxic potential of cannabis on human brain function. We studied non-acute effects of frequent cannabis use on hippocampus-dependent associative memory, investigated with functional Magnetic Resonance Imaging (fMRI) in 20 frequent cannabis users and 20 non-users matched for age, gender and IQ. Structural changes in the (para)hippocampal region were measured using voxel-based morphometry (VBM). Cannabis users displayed lower activation than non-users in brain regions involved in associative learning, particularly in the (para)hippocampal regions and the right dorsolateral prefrontal cortex, despite normal performance. VBM-analysis of the (para)hippocampal regions revealed no differences in brain tissue composition between cannabis users and non-users. No relation was found between (para)hippocampal tissue composition and the magnitude of brain activity in the (para)hippocampal area. Therefore, lower brain activation may not signify neurocognitive impairment, but could be the expression of a non-cognitive variable related to frequent cannabis use, for example changes in cerebral perfusion or differences in vigilance.
Jager
Gerry
G
Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, A.01.126, University Medical Center, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands. gjager@umcutrecht.nl
Van Hell
Hendrika H
HH
De Win
Maartje M L
MM
Kahn
Rene S
RS
Van Den Brink
Wim
W
Van Ree
Jan M
JM
Ramsey
Nick F
NF
D000328:Adult; D001245:Association Learning / Q000187:drug effects / Q000502:physiology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006624:Hippocampus / Q000098:blood supply* / Q000503:physiopathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D002189:Marijuana Abuse / Q000473:pathology / Q000503:physiopathology*; D011939:Mental Recall / Q000187:drug effects / Q000502:physiology*; D009483:Neuropsychological Tests; D010100:Oxygen / Q000097:blood
D010100:Oxygen