Effect of baseline cannabis use and working‐memory network function on changes in cannabis use in heavy cannabis users: A prospective fMRI study

摘要

Theoretical models of addiction suggest that a substance use disorder represents an imbalance between hypersensitive motivational processes and deficient regulatory executive functions. Working‐memory (a central executive function) may be a powerful predictor of the course of drug use and drug‐related problems. Goal of the current functional magnetic resonance imaging study was to assess the predictive power of working‐memory network function for future cannabis use and cannabis‐related problem severity in heavy cannabis users. Tensor independent component analysis was used to investigate differences in working‐memory network function between 32 heavy cannabis users and 41 nonusing controls during an ‐back working‐memory task. In addition, associations were examined between working‐memory network function and cannabis use and problem severity at baseline and at 6‐month follow‐up. Behavioral performance and working‐memory network function did not significantly differ between heavy cannabis users and controls. However, among heavy cannabis users, individual differences in working‐memory network response had an independent effect on change in weekly cannabis use 6 months later (Δ = 0.11, = 0.006, = 0.37) beyond baseline cannabis use (Δ = 0.41) and a behavioral measure of approach bias (Δ = 0.18): a stronger network response during the ‐back task was related to an increase in weekly cannabis use. These findings imply that heavy cannabis users requiring greater effort to accurately complete an ‐back working‐memory task have a higher probability of escalating cannabis use. Working‐memory network function may be a biomarker for the prediction of course and treatment outcome in cannabis users. . © .