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The effects of exercise on regional brain activation in response to smoking cues during temporary abstinence from smoking
Kate Janse Van Rensburg, PhD Student, University of Exeter
Abstract
The presence of substances of misuse (such as nicotine) are associated with increases in brain activation within the meso-corticolimbic brain system, which is thought to mediate the rewarding effects of most drugs (Koob & LeMoal, 2001).
Pharmacological treatments for the control of nicotine addiction (such as bupropion) have been designed to attenuate the rewarding effects of cigarette smoking (Balfour, 2001). These drugs are thought to suppress the pathological ‘need’ to consume nicotine by acting upon the brain circuits involved. Exercise has been found to be an effective non-pharmacological tool for controlling cigarette cravings (Taylor et al., 2007). One proposed mechanism suggests that exercise may increase dopaminergic stimulation in the forebrain, thus reducing craving for drug utilisation.
On the same day, in a within-subject cross-over design, regular smokers (n=10) were initially randomised to begin with either an exercise (10 minutes stationary cycling at a Rating of Perceived Exertion of 11-13) or control (passive seating) session, following 8 hours of CO confirmed nicotine abstinence. Immediately following each treatment, participants entered a functional magnetic resonance imagery scanner (fMRI)(1.5 T Philips Gyroscan magnet). Both fMRI sessions involved viewing a random order of 60 images (30 smoking/30 neutral), each for 3 seconds, with an average inter-stimulus-interval of 10 seconds. A reaction time probe task maintained alertness during the scanning. Self-reported cravings (using the 7-point ‘I have a desire for a cigarette right now’ Tiffany & Drobes, 1991) were assessed at baseline, post treatment and after exiting the MRI scanner.
A 2 (pre-post treatment) X 2 (exercise-control) fully repeated measures ANOVA revealed a significant interaction effect of time x group on desire to smoke F (1) = 12.06, p = .007. Post treatment, means (SD) were 3.10 (1.45) and 4.80 (1.69) for the exercise and passive control conditions (effect size = 1.08), respectively. Post exercise scanning was associated with a down-regulation of brain activation in the orbitofrontal area of the forebrain (in contrast with the passive condition).
Reduction in activation of the orbitofronatal cortex (which forms part of the mesocortical dopamine circuit) may suggest that exercise has the ability to reduce the perceived incentive salience of the drug and the craving for the drug (Goldstein & Volkow, 2002). This is the first study to explore neurobiological mechanisms for how exercise acutely reduces cigarette cravings and adds support to the role that exercise can play in the management of cue-elicited cigarette cravings.
Biography
Kate Janse van Rensburg is a 1st year PhD student in the Schools of Sport & Health Sciences (SSHS) and Psychology, jointly supervised by Drs Adrian Taylor and Dr Tim Hodgson, at the University of Exeter. She conducted a study on the acute effects of exercise on cigarette cravings and cognitive functioning for her MSc dissertation in SSHS. Dr Adrian Taylor is an Associate Professor in Exercise and Health Psychology, in SSHS. He has published 11 peer reviewed journal articles on the role of exercise as an aid to smoking cessation, in esteemed journals such as Psychopharmacology, Addiction, Nicotine & Tobacco Research, Addictive Behaviours, and Patient Education and Counselling. His broader research focus is on the mental health benefits of exercise, and he is currently involved in 3 exercise trials and a national feasibility study (Walk-2-Quit) on promoting exercise within NHS Stop Smoking Clinics. Dr Tim Hodgson is a Senior Lecturer in Cognitive Neuroscience in the School of Psychology. He has published research in esteemed journals such as Neuropsychologia, Experimental Brain Research, Journal Of Cognitive Neuroscience, Neuroimage, Nature Neuroscience and Brain.
Kate Janse Van Rensburg
92 Waterside,
Haven Banks
Exeter
EX2 8GZ
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