Acute Effects of Nicotine on Non-Drug-Related Reward in Smokers and Non-Smokers.

Introduction: Nicotine increases the reward value of non-drug-related stimuli in animals and dependent smokers; however, research on people who are not dependent on nicotine is limited. This study aimed to explore whether nicotine delivered by oral spray can enhance responding to self-selected sensory rewards in both smokers and non-smokers.

Aims and methods: Minimally abstinent smokers (n = 30) and non-smokers (n = 31) completed subjective ratings of nicotine withdrawal, and received either 2 mg nicotine or placebo oral spray and visual analogue scales to measure the perceived effects of the spray. An operant conditioning task (Applepicker) that required button clicks to find apples was completed twice, with and without a reward of 30 seconds of pre-prepared music for each reinforcer earned. Measures taken were the number of apples found (reinforcers), number of clicks (responses), and time spent on the task (in seconds).

Results: There were no differences between smokers and non-smokers on ratings of nicotine withdrawal or effects of the spray. All participants spent longer searching for apples, earned more reinforcers, and produced more responses when listening to music. Nicotine administration led to a higher number of reinforcers earned and, when music was playing, an increase in a number of responses. A three-way interaction revealed that non-smokers who had received nicotine spent the longest searching for apples.

Conclusions: Nicotinic enhancement of sensory rewards was seen in non-smokers only which cannot be accounted for by learned associations with nicotine or reversal of withdrawal effects. Smokers, however, may require higher doses of nicotine to achieve the same effect.

Implications: Nicotinic enhancement of sensory rewards was demonstrated in non-smokers, but not in everyday smokers, suggesting it is unlikely to be related to nicotine dependence or learned associations between nicotine and pleasure. The absence of this effect in smokers suggests that higher levels of nicotine than those obtained from 2 mg oral sprays may be required to achieve enhancement of reward in people who regularly consume nicotine. For nicotine replacement (including e-cigarettes) to become more effective at reducing anhedonia during quit attempts, smokers may require nicotine doses that more closely replicate levels achieved through smoking.