Dm. Warburton et al., Improved incidental memory with nicotine after semantic processing, but not after phonological processing, PSYCHOPHAR, 153(2), 2001, pp. 258-263
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.