Improved incidental memory with nicotine after semantic processing, but not after phonological processing

Rationale: A number of lines of evidence suggest that a nicotinic cholinerg ic system is mediating attentional processing. However, the evidence is les s clear for a nicotinic system being involved in mnemonic processing. Objec tives: The present study investigated the effects of nicotine on memory usi ng a depth of processing paradigm. Methods: A double-blind design was used with participants (n=40) smoking either a nicotine containing cigarette (n= 20) and a denicotinized cigarette (n=20). After smoking, each set of these participants was further subdivided into two groups (n=10 for each). One gr oup were presented with a series of trials each beginning with the presenta tion of a "decision word" which they had to say whether it represented some thing which was living or non-living (semantic-orienting). The second group had to say whether the word had one syllable or two syllables (phonologica l or non-semantic orienting condition). This decision was followed by a wor d in coloured ink whose colour participants were required to name as quickl y as possible. On completion of the whole task the participants were given an unexpected free recall test. Results: The nicotine-containing cigarette reduced the latencies for decision-making and colour naming in comparison w ith the denicotinized cigarette. The free recall test showed that nicotine- containing cigarette increased the number of words remembered, but only for the semantic-orienting condition and not the non-semantic condition. Concl usions: There is a nicotinic cholinergic system that mediates effortful pro cessing. It can be deployed for attentional processing, including the assoc iative processing required for memory encoding.