d-amphetamine increases choice of cigarette smoking over monetary reinforcement

Abstract

Rationale: Psychomotor stimulants previously have been found to increase the frequency of cigarette smoking, but it is unclear whether this is due to a non-specific increase in general activity or a specific increase in the reinforcing effects of smoking.

Objectives: To investigate whether d-amphetamine increases the relative reinforcing effects of cigarette smoking.

Methods: Ninety minutes after d-amphetamine (7.5, 15 mg/70 kg) or placebo administration, 13 male and female subjects participated in 3-h sessions during which they could make a maximum of 20 choices between cigarette smoking (two puffs per choice), earning money ($0.25 per choice), or neither. In separate sessions, using the same subjects, the effects of d-amphetamine on the frequency of ad libitum smoking was assessed.

Results: During choice sessions, d-amphetamine dose-dependently increased smoking choices from 4.2 +/- 0.6 to 5.7 +/- 0.6. During sessions in which subjects smoked ad libitum, d-amphetamine increased number of cigarettes smoked from 2.8 +/- 0.4 to 3.8 +/- 0.6. Breath carbon monoxide (CO) levels, a measure of smoke exposure, showed corresponding dose-related increases.

Conclusions: These results are consistent with previous findings that d-amphetamine increases smoking and provide evidence that this effect is due to a drug-produced increase in the relative reinforcing effects of cigarette smoking.