“…While some show enhancement of ''normal'' memory as a result of nicotine treatment (Wesnes and Warburton, 1984;Levin et al, 1987Levin et al, , 1993Levin et al, , 1997Levin et al, , 2001Bancroft and Levin, 2000;Bettany and Levin, 2001;Swan and LessovSchlaggar, 2007; for review), others report no effect (Dunne et al, 1986;Parrott and Winder, 1989;Aleisa et al, 2006c;Alzoubi et al, 2006b), and even memory impairment (Sorenson et al, 1991;Park et al, 2000). In humans, however, the literature that describes nicotine effect on memory is sometimes confounded by the use of smokers as subjects (Swan and Lessov-Schlaggar, 2007;for review).…”