Running head: HABIT PROPENSITY AS A VULNERABILITY FACTOR FOR DEPENDENCE IN EXPERIMENTAL SMOKERS AND NON-SMOKERS
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Many Dutch adolescents have tried smoking, thereby risking the chance to become dependent on nicotine. In dependence, individuals show more habitual behaviour and less goal-directed behaviour. Dependent individuals might also activate the goal-directed brain system (the ventromedial prefrontal (VMPFC) cortex and ventral striatum) less and the habitual system (dorsal striatum) more. However, it is still unclear whether there are pre-existing differences in brain and behaviour that might indicate susceptibility to dependence. To test this, in the current study 8 experimentally smoking adolescents and 10 non-smoking controls participated in the slips-of-action task in the fMRI scanner to test differences in goal-directed and habitual behaviour and their corresponding brain systems between the two groups. It was expected that experimental smokers would be more habitual and less goal-directed compared to the nonsmokers, indicating that habit propensity could be indicated as a risk factor to dependence. In addition, experimental smokers were expected to activate the goal-directed brain system (VMPFC and ventral striatum) less and the habitual (dorsal striatum) brain system more. However, there were no behavioural differences between both groups, nor were there differences in activity in the VMPFC, ventral and dorsal striatum between the groups. These findings may suggest that the differences between dependent and non-dependent individuals are not pre-existing, thus habit propensity might not indicate vulnerability to dependence. Due to the very small sample size and the difficulty of the task, however, validation of these results in a bigger sample is highly warranted.
Faculteit der Sociale Wetenschappen