Functional MRI evidence for inefficient attentional control in adolescent chronic cannabis abuse

Control of attention is a key mechanism underlying behavior regulation. In this study we detail the aspects of attention that covary with the chronic use of cannabis throughout adolescence. We compared performance and brain activation differences in tasks involving attention between young adults with a history of chronic cannabis use during adolescence and matched non-user control subjects. Two tasks were used to activate attention networks: the Attention Network Task (ANT) and the use generation task. In the ANT, chronic users (N = 14) differed from controls (N = 14) in showing poorer performance (longer reaction time and more errors) on tasks requiring processing of incongruent stimuli reflecting the executive attention network, but not in networks related to alerting or orienting components of attention. Functional MRI of brain activity showed stronger activation within the right prefrontal cortex in chronic users compared to the control group specifically on ANT trials requiring executive attention. The use generation task also revealed significantly stronger activation of the same right prefrontal area in users compared to controls. These results suggest that chronic cannabis users have less efficient executive attention in conflict resolution tasks, demanding more activation in the right prefrontal areas to resolve conflict.

Yellow shows increased activation in cannabis abuse compared to control group; Blue shows decreased activation in cannabis abuse compared to control group.Figure optionsDownload high-quality image (48 K)Download as PowerPoint slideResearch highlights▶ Chronic adolescent cannabis abuse is associated with poor performance in executive attention network related to conflict resolution, but not in alerting or orienting networks of attention. ▶ Poor performance in executive attention is associated with increased right prefrontal activation in attention tasks. ▶ Increased right prefrontal activation and the anterior cingulate deactivation become more pronounced with increasing task difficulty.