Cortico-cerebellar abnormalities in adolescents with heavy marijuana use.

There are currently no studies that have evaluated the motor network, including the cerebellum, in adolescent marijuana (MJ) smokers. The current study aimed to evaluate whether there were activation differences in Brodmann's area 4 (BA4), Brodmann's area 6 (BA6), cingulate (CG) and cerebellum between MJ-using adolescents and healthy controls (HC) on a functional magnetic resonance imaging (fMRI) bilateral finger-tapping task. Twenty-four adolescents (aged 18.2 ± 0.7 years) with heavy MJ use and 24 HC (18.0 ± 1.9) had MRI scans on a 3T Siemens scanner, including a standard bilateral fMRI finger-tapping sequence. Imaging data were analyzed using SPM5 in Matlab. As regions of interest, BA4, BA6, cingulate (CG) and cerebellum were selected, and significant clusters of activity were thresholded at p<0.05, corrected. Healthy controls had significantly greater activation than MJ users for the CG and cerebellum. In addition, activation of the cerebellum and CG correlated with lifetime MJ smokes. This is one of the first studies to evaluate cortico-cerebellar circuits in adolescents with heavy MJ use. The study, which used a bilateral finger-tapping fMRI task, provides evidence for both CG and cerebellar dysfunction in MJ abuse and indicates that lifetime MJ use may impact the developing brain. Published by Elsevier Ireland Ltd.