In addition to improvement in attention, smoking improves withdrawal symptoms, such as depressed mood, anxiety, and irritability in tobacco-dependent smokers (Cohen et al. 1991; Parrott 2003), and all these effects depend (at least in part) on the expectations of the smoker (Perkins et al. 2003). Though nicotine administration generally results in increased activity along prefrontal and paralimbic brain circuits, it is interesting that both increased and decreased ACC activation during cognitive task performance has been reported (see Sect. 2.2). ACC activity has been associated with anxiety and mood, with increased activity being associated with greater anxiety (Chua et al. 1999; Kimbrell et al. 1999) and decreased activity being associated with depressed mood (Drevets et al. 1997). This combination of findings suggests a potential interaction between expectation of the effects of smoking (e.g., mood improvement, anxiety reduction, or decreased irritability) and direction of ACC activity change during cognitively demanding tasks. Perhaps smokers who expect to and do have anxiety alleviation from smoking have deactivation or decreased activation of the ACC while performing cognitive tasks, whereas those who expect to and do experience mood improvement from smoking have increased activation of the ACC.
