The role of inhibitory control and reward sensitivity in impulsive behaviours; relevance for alcohol abuse

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Theodora Duka; MD PhD
Behavioural and Clinical neuroscience, School of Psychology, University of Sussex, UK
Alcohol is known to reduce inhibitory control and support impulsive behaviours. In two studies we examine alcohol acute effects on impulsivity as well as on the relationship between impulsive behaviours and alcohol abuse. Four behavioural subtypes of impulsivity in humans were analysed ‘reflection’- (decision making without gathering or evaluating information) and ‘temporal’- (failure to delay gratification) impulsivity as two forms of cognitive-impulsivity, and ‘motor’- impulsivity in the form of “can’t stop” or “can’t wait” as an action related impulsivity.
Alcohol in the dose of 0.8g/kg increased motor impulsivity both in the “can’t stop” and “can’t wait” form, but decreased temporal impulsivity. Although both forms of motor impulsivity were affected by alcohol, only “can’t wait” impulsivity was associate with alcohol abuse. Alcohol in the same dose was also found to accentuate impulsive behaviour, which leads to ignoring damaging consequences (when in competition with reward); this type of impulsive behaviour was mediated by reduced inhibitory control and was associated with BOLD changes in a cluster including the inferior orbitofrontal cortex (B47).
These data suggest that risky and aggressive behaviours following alcohol binges must be derived mostly by reduced inhibitory control contributing to motor impulsivity. The effects of alcohol on reward sensitivity may lead to ignoring the damaging consequences of heavy drinking. The differential role of reward sensitivity and weakening of inhibitory control in impulsive behaviours and their implications for alcohol abuse will be the main focus of the presentation.