Mechanisms of addiction and relapse: Startling evidence for lingering appetitive effects of drug-cues in smokers and former smokers

Abstract

Background and aims:

Implicit memories like consumption habits and conditioned reactions to drug-related stimuli are operational in addiction and relapse. The affective startle paradigm is an attractive tool for the measurement of the incentive salience of drug-related cues. We tested whether the stronger appetitive valence of drug cues, shown in two recent startle studies in smokers, does persist after prolonged abstinence, and may thus contribute to relapse.

Method:

We examined the auditory startle reflex magnitude of mildly deprived (4-6 hours) heavy smokers (n = 24), former smokers (n = 16, mean abstinence interval 18 months), and non-smokers (n = 24) while they viewed smoking-related scenes or standardized unpleasant, neutral and pleasant control scenes from the International Affective Picture System.

Results:

As expected, non-smokers showed no appetitive reactions toward smoking-cues. In smokers, smoking-cues had both appetitive implicit (startle suppression) and explicit (ratings for valence and craving) motivational effects, resembling those of pleasant scenes and differing from neutral and unpleasant scenes. This effect was more pronounced in smokers who later relapsed after a smoking cessation program, and in smokers consuming less than 20 cigarettes per day. Former smokers, despite reporting no craving and negative reactions to smoking cues, still showed evidence of implicit appetitive valence of these cues.

Conclusions:

Nicotine addiction results in automatic appetitive reactions to drug-cues, which does not vanish after prolonged abstinence and which may thus contribute to relapses. Heavy smoking may result in a progressive internalization of smoking habits and a decline in reactivity towards external smoking-associated cues.