Effects of Repetitive Transcranial Magnetic Stimulation to the Dorsolateral Prefrontal Cortex on Withdrawal and State Anxiety in People Who Smoke Cigarettes

Abstract

Abstinence from cigarettes is associated with withdrawal and anxiety symptoms, which are barriers to smoking cessation. Repetitive Transcranial Magnetic Stimulation (rTMS) reduces both withdrawal and anxiety symptoms; however, the extent to which withdrawal reductions depend on anxiety reductions isn’t known, which this study was designed to address. The two predictions were that 1) there would be a positive relationship between withdrawal symptoms and state anxiety (anxiety symptoms in the present moment) and 2) rTMS-related reductions in state anxiety would mediate reductions in withdrawal. Participants (N = 44) were adults ages 18 - 45 who reported daily use of 5+ cigarettes for 1+ years. Participants received single-session rTMS (10 Hz at 100% of motor threshold; 5s on; 10s off; 3000 pulses total) to the left dorsolateral prefrontal cortex (dlPFC; experimental site) and the visual cortex (v5; control site) in a randomized, crossover, single-blind, within-subjects design. They completed the Shiffman-Jarvik Withdrawal Scale (SJWS) and the State-Trait Anxiety Inventory (STAI) before and after each rTMS treatment. There were significant positive correlations between withdrawal and state anxiety before and after rTMS, p < .001. A mixed-effects linear model indicated that rTMS to dlPFC led to a significant reduction in SJWS craving subscale scores, p < .05. However, a mediation analysis suggested that state anxiety did not mediate the reduction in SJWS scores, p > .05. Withdrawal and state anxiety were positively related before and after rTMS, and rTMS to dlPFC reduced cigarette craving. Reductions in cigarette craving by rTMS were not mediated by effects of rTMS on feelings of anxiety. With the goal of understanding how rTMS influences the cognitive and affective markers of smoking, this study was a step towards elucidating the psychological mechanisms of rTMS on cigarette withdrawal and craving.