Direct and indirect effects of nicotine/smoking on cognition in humans.

Acute nicotine administration and acute nicotine withdrawal have been shown to have effects on mood, arousal, and cognition in humans. However, given what is known about the interrelationships between mood, arousal, and cognition in the psychology literature, it is unclear to what extent these effects on a given response are direct, or mediated through other responses (indirect). This article discusses this issue with particular emphasis on the question of whether nicotine has direct effects on cognition. Five ways are suggested as to how this question can be resolved, the relevant literature is reviewed, and some research ideas are proposed.