Attentional abilities nicotine

The central nervous actions of nicotine are thought to be mediated largely by presynaptic receptors that facilitate transmitter release from excitatory aminoacidergic (glutamatergic) nerve terminals in the cerebral cortex. Nicotine increases vigilance and the ability to concentrate. The effect reflects an enhanced readiness to perceive external stimuli (attentiveness) and to respond to them. 

As discussed previously, results of studies conducted with nicotine-deprived smokers are difficult to interpret. Without pre-deprivation baseline data, which few studies report, it is difficult to conclude whether nicotine reversed deprivation-induced deficits or enhanced performance beyond that observed in the nondeprived state. In general, however, nicotine and smoking at least reversed deprivation-induced deficits in certain abilities in abstinent smokers, but such beneficial effects have not been observed consistently across a range of performance measures. For example, about half of the studies that measured sustained attention and memory reported a positive effect of nicotine however, the effects were limited to some subjects or one aspect of test performance. 

In humans, nicotine is reported to increase arousal and attention as well as decrease reaction time and prevent decline in efficiency over time (Wesnes and Warburton, 1983, 1985). In both animals and humans nicotine improves the subject s ability to withhold responses to inappropriate stimuli (Myrsten et al., 1972 Wesnes and War-burton, 1983 Newhouse et al., 1988). This may be relevant to AD because a cardinal feature of the cognitive disorder of AD and a possible marker of cholinergic dysfunction (Fuld et al., 1982) is the difficulty demented patients have in inhibiting inappropriate responses or in responding to inappropriate stimuli. This difficulty in response selection and/or suppression is one explanation of the liberal response bias seen in AD. Gray et al. (1996) have shown that nicotine enhances hippocampal synaptic transmission which may be critical for new learning to take place. 

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