Excessive alcohol consumption and dependence on amphetamine are associated with parallel increases in subjective ratings of both ‘wanting’ and ‘liking’

Aim: One of the tenets of the incentive sensitization theory of drug addiction is that 'as drugs come to be wanted more and more, they often come to be liked less and less'. The aim of this study was to test whether this assumption holds true. Specifically, the study aimed to test the hypothesis that in non-clinical samples, dependence on amphetamines and excessive alcohol use are associated with increased 'wanting' but decreased 'liking' for the drug. Design, setting and participants: In two studies, the Desires for Alcohol Questionnaire (DAQ) was administered to 380 recreational drinkers, and the Desires for Speed Questionnaire (DSQ) and the Leeds Dependence Questionnaire (LDQ) were administered to 174 amphetamine users. Scales were derived from the DAQ and DSQ representing craving, on one hand, and positive and negative reinforcement on the other hand. Craving and positive reinforcement were taken as measures of alcohol or amphetamine 'wanting' and 'liking', respectively. Findings: Scores on all three DAQ scales increased monotonically as a function of the extent of alcohol consumption. Scores on all three DSQ scales increased monotonically as a function of dependence, as measured by the LDQ. 'Liking' for amphetamine was unrelated to time since the drug was last taken. (These data were not available for alcohol.) Conclusions: The finding that 'wanting' increased as a function of dependence on amphetamine or level of consumption in the case of alcohol is as predicted by the incentive sensitization theory, but the finding that 'liking' also increased as a function of dependence or excess is the opposite of the predicted effects While not refuting the incentive sensitization theory directly, the study questions the validity of one of the tenets of the theory