Assessing Within-Task Time Course of Cognitive Interference Processing in Recreational Marijuana Users
Abstract: Marijuana (MJ) remains the most popular illicit drug in the US; however, chronic, heavy MJ use is often associated with cognitive decrements, particularly poorer executive functioning, with earlier age of onset of MJ use associated with increased impairment. Further, neuroimaging studies have demonstrated dysfunctional activation of the cingulo-fronto-parietal attention (CFP) network, ... read moreparticularly within the cingulate and dorsolateral prefontal cortices (DLPFC), of MJ users. This dissertation assesses the impact of chronic, heavy MJ use on cognitive interference, one aspect of executive function associated with attentional shifting and inhibitory control, using the Multi-Source Interference Task (MSIT). Although MJ-associated alterations in CFP activation during the MSIT have previously been reported, task performance differences have been inconsistent; however, previous studies only examined task performance and fMRI activation averaged across the whole task. The current research examined changes in performance and brain activation patterns over the course of the task using two-group (control vs MJ) analyses as well as three-group (control vs early MJ onset vs late MJ onset) analyses in order to assess the impact of age of MJ onset. Results indicate that MSIT performance and brain activation are dynamic over time in both control participants and MJ users. Even though significant between-group task performance differences were not observed, cingulate and DLPFC activation patterns were altered in MJ users. MJ users demonstrated increased activation over time, which was sustained throughout longer periods of the task relative to control subjects. However, when MJ users were divided based on age of MJ onset, the late MJ onset group demonstrated a pattern of activation more similar to the control group, with the greatest activation observed during the initial blocks, and attenuated activation over time, whereas the early MJ onset group demonstrated a more dysfunctional pattern of activation with greater activation during later blocks. Additionally, increased DLPFC activation in early MJ users and decreased cingulate activation in late MJ users were both related to greater task difficultly during cognitive interference processing, and aspects of MJ use (particularly earlier age of onset) was associated with both poorer performance as well as altered CFP activation.
Thesis (Ph.D.)--Tufts University, 2018.
Submitted to the Dept. of Psychology.
Advisors: Heather Urry, and Staci Gruber.
Committee: Scott Lukas, Elizabeth Race, and Robin Kanarek.
Keywords: Psychology, Clinical psychology, and Experimental psychology.read less