2. Resting state functional connectivity of the dorsal attention network in cannabis use disorder: a fMRI study
Introduction/issues: Regular cannabis use is associated with altered attention processing and performance. The dorsal attention network (DAN) focuses the brain’s attention towards task-related visual stimuli and has been linked to impaired cognitive performance and psychotic-like symptoms. Disruptions in the DAN may underlie altered visual salience processing and increased psychosis vulnerability in cannabis use disorder (CUD), however this has not been investigated.
Design and methods: In this cross-sectional study, we compared the average strength of resting state functional connectivity in the DAN in regular cannabis users who meet DSM-5 criteria for severe (n=29) versus mild (n=21) CUD, and non-using controls (n=26). The average network strength was defined as the z-transformed Pearson’s correlation coefficient between the mean time-series of all network nodes using the Gordon Atlas. Linear mixed-models examined group differences and interactions with psychotic-like symptoms using the Schizotypal Personality Questionnaire (SPQ).
Key findings: Severely dependent cannabis users had greater average network strength in the DAN compared to mildly dependent users (p=.04) and non-users (p=.02). Greater network strength in the severely dependent group was associated with more SPQ disorganised symptoms (p=.04), while the opposite direction was observed in mildly dependent users (p<.01).
Discussions: Hyper-connectivity of DAN strength was found in severely dependent cannabis users. Differential associations between disorganised symptoms and network strength as a function of CUD severity may indicate an increased vulnerability of psychotic-like symptoms in severe CUD. We will further examine the significance of these findings in relation to attentional bias and reward-related attentional capture in the same sample of participants.