Human aggressive responding during acute tobacco abstinence: effects of nicotine and placebo gum

Aggressive and point maintained operant responding of heavy nicotine dependent male tobacco smokers were measured during five 25-min sessions conducted over an 8-h period. Responding under three tobacco abstinence conditions was compared to responding during a baseline condition of ad libitum smoking of the subject's preferred brand of cigarettes. The three tobacco abstinence conditions were: (1) placebo gum, (2) nicotine gum or (3) no gum. Under placebo and nicotine gum conditions, subjects were given two pieces of placebo or 2 mg nicotine gum to chew for 30 min prior to each session. Expired air carbon monoxide (CO) levels were measured at the end of each session to monitor smoking under baseline conditions and compliance with non-smoking requirements under abstinence conditions. Aggressive responding was increased in no gum and placebo gum conditions, with the highest frequency of aggressive responding occurring under no-gum conditions. Aggressive responding during nicotine gum conditions did not differ from baseline ad libitum tobacco smoking. Point maintained responding was either not affected or decreased under placebo and no-gum conditions. These results provided objective data consistent with clinical reports of increased irritability among dependent tobacco smokers during acute tobacco abstinence.