Associations between regular cannabis use and brain resting-state functional connectivity in adolescents and adults

Cannabis use is highly prevalent in adolescents however little is known about its effects on adolescent brain function. Resting-state functional Magnetic Resonance Imaging was used in matched groups of adolescents (16-17 years old, N=70, 35 users/35 controls) and young adults (26-29 years old, N=70, 35 users/35 controls). Pre-registered analyses examined the connectivity of cortical and sub-cortical brain networks. Cannabis users (across both age-groups) showed localised increases in connectivity in the default mode, executive, and limbic striatum networks. Localised decreases in connectivity were seen in the salience network, and the sensorimotor striatal network showed both localised increases and decreases in connectivity. Mean connectivity across entire networks was significantly decreased in the default mode network in cannabis users. There were no significant interactions found between age-group and user-group. Cannabis use is associated with changes to connectivity in cortical and sub-cortical brain networks, however adolescence does not appear to modify these effects.