Borissova, A. | bioRxiv Science

bioRxiv2026

Longitudinal fMRI reveals altered developmental trajectories of functional network organisation associated with adolescent cannabis use

Adolescence is a critical period of brain development during which the endocannabinoid system continues to mature. These developmental changes may contribute to age-related differences in the association between cannabis use and large-scale functional network organisation, yet this association remains incompletely characterised. We hypothesised that regular cannabis use would be associated with differential one-year changes in resting-state functional connectivity between adolescents and adults. Resting-state fMRI data at two time points, one year apart, were analysed from 66 participants (31 aged 16-17 years; 35 aged 26-29 years) including 29 with regular cannabis use and 37 age-matched cannabis-naive controls. Seed-to-voxel analyses examined longitudinal changes in functional connectivity across age and cannabis-use groups. Year change, age by user-group interactions were identified in salience and default mode network connectivity, including divergent changes in anticorrelations with medial prefrontal, thalamic, cerebellar and juxtapositional regions. Directionality of effects differed by network and region. Additional main effects of user group were observed for executive control and associative striatal connectivity, with the cannabis-use group showing decreased positive connectivity and reduced anticorrelation, respectively. Changes in functional connectivity were developmentally dissociable and predominantly observed in regions contributing to attentional and transmodal processing. These findings suggest that cannabis may be associated with alterations in the maturational refinement of higher-order neural systems, potentially reflecting age-related differences in neurobiological sensitivity to cannabis exposure. Considering developmental stage may therefore be important for characterising cannabis-related neurobiological differences and may have implications for understanding age-dependent vulnerability to cannabis-related psychiatric outcomes.

neuroscience↗

bioRxiv2022

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 cannabis users (N=70, 35 adolescents16-17 years old, 35 adults 26-29 years old) and non-users (N=70, 35 adolescents/35 adults). Pre-registered analyses examined the connectivity of seven major cortical and sub-cortical brain networks (default mode network, executive control network, salience network, hippocampal network, and three striatal networks) using seed-based analysis methods with cross-sectional comparisons between user groups, and age groups. Cannabis users (across both age-groups), relative to controls, showed localised increases in connectivity only in the executive control network analysis. All networks showed localised connectivity differences based on age group, with the adolescents generally showing weaker connectivity than adults; consistent with developmental effects. Mean connectivity across entire network regions of interest (ROIs) was also significantly decreased in the executive control network in adolescents. However, there were no significant interactions found between age-group and user-group in any of the seed-based or ROI analyses. There were also no associations found between cannabis use frequency and any of the derived connectivity measures. Chronic cannabis use is associated with changes to connectivity of the executive control network, which may reflect allostatic or compensatory changes in response to regular cannabis intoxication. However, these associations were not significantly different in adolescents compared to adults.

neuroscience↗