Disinhibition and alcohol consumption

The current thesis aimed to explore the relationship between disinhibition and alcohol consumption in non-dependent drinkers. Specifically, whether (dis)inhibition can be considered a ‘state’ variable, which is responsive to motivational biases, cues and training. It was examined whether any fluctuations in (dis)inhibition could influence subsequent ad-libitum alcohol consumption, in sober individuals (de Wit, 2009). Furthermore, the effects of beliefs about disinhibition, exclusively in relation to alcohol-seeking, were also examined with respect to possible effects on alcohol-seeking. These general research questions were examined in a heavy drinking, student population. Chapter One discussed in detail the relationship between disinhibition and alcohol consumption by examining evidence from relevant models of addiction. Chapter Two described the general methods used in the experimental chapters of the thesis. In the first experimental chapter (Chapter Three) individuals were primed with different motivational biases on how to respond on a stop-signal task, before ad-libitum consumption was measured. Different motivational biases led to group differences in inhibition performance, it was demonstrated that a restrained mental set led to a reduction in alcohol consumption in the laboratory. Expanding this finding, Chapter Four examined the effect of these motivational biases on neuropsychophysiological measures (Event Related Potentials and Source dipole analyses) of inhibitory control; associations between inhibition indices and ad-libitum consumption were discussed. Chapter Five set out to examine whether inhibitory control could be trained specifically to alcohol cues, and whether this training could serve to reduce alcohol consumption in the laboratory (Experiment One and Two) and outside the laboratory (Experiment One) in response to emerging research (Houben et al 2011a). Two different types of inhibition training, motor and oculomotor, were compared in this chapter. Results demonstrated some success for motor, but not oculomotor inhibition, in both training behaviour and reductions in alcohol consumption, highlighting the fundamental differences in these constructs. Chapter Six examined whether alcohol cues could cause disinhibition in heavy social drinkers, but found no evidence for cue-related disinhibition. However, some evidence for disinhibition and cue-reactivity was established and possible methodological issues discussed. In the final experimental chapter (Chapter Seven) restraint beliefs were examined in relation to ad-libitum alcohol consumption. It was found that beliefs could influence ad-libitum alcohol-seeking, however results were at first glance paradoxical to behavioural research. The overall results of this thesis offer some of the first experimental support for the causal relationship between state disinhibition and alcohol consumption in sober, non-dependent individuals. Support was offered for the theories of addiction that postulate the association between disinhibition and alcohol consumption, specifically recent models that suggest disinhibition is a state which can influence drinking behaviour. Finally, support for recent theories that suggest targeting controlled processes may serve to reduce alcohol consumption in populations at high risk for alcohol abuse.