DISRUPTION OF IMPULSIVITY BEHAVIORS IN CANNABIS USERS IN ADOLESCENTS AND YOUNG ADULTS: A META-ANALYSIS OF FUNCTIONAL NEUROIMAGING STUDIES

Abstract Background Cannabis is a widely used controlled psychoactive substance. Increased dopamine excitation transmission reduced the capacity of controlling impulsivity behaviors which contributed to their growing desire to drugs, especially teenager and young adults. In cannabis users, the effect of cannabis on impulsivity control behaviors mainly reflected in impulsivity control, inhibitory control and delayed reward discounting, however no unified conclusion has made. Aims & Objectives We sought to perform a meta-analysis to clarify the effect of cannabis use on impulsivity control behaviors and dynamic changes of brain regions during impulsivity control process of cannabis users in teenage and early adulthood. Method A systematic search of the PubMed, Embase and Web of Science was performed to identify fMRI studies that were published from the inception up to August 20th, 2023, which reported the brain activation during impulsivity control process of cannabis users in teenage and early adulthood. Backward citation tracking was also performed. Seed-Based d Mapping (SDM) was applied to combine the statistical maps, coordinates and t-values of the peaks in each study. We concerned the sources of heterogeneity by subgroups and meta-regression. Results 28 studies with 1381 individuals were included in the analysis. Compared to healthy controls, cannabis users in adolescents and early adulthood showed weakened impulsivity control capacity. Besides, cannabis users during abstinence period showed increased responses in bilateral anterior thalamic projections and cingulate cortex during impulsivity control process compared with healthy controls. Further, cannabis users with early onset age showed worse inhibition capacity in cingulate cortex and medial prefrontal cortex. Increased activation in cingulate cortex and better inhibition in striatum were correlated with better performance in impulsivity control tasks. Discussion & Conclusion This review and meta-analysis indicates attenuation in impulsivity control behaviors in teenage and early adulthood cannabis users. During impulsivity control process, increased activation in cingulate cortex was shown in adolescents and early adulthood cannabis users. Earlier cannabis intake could cause dysregulation of cingulate cortex and medial prefrontal cortex in impulsivity control process. Protective measures should be taken to reduce the possibility of adolescents' exposure to cannabis and attenuate the damage of cannabis to the brain.