of major depression is associated with a greater prevalence of smoking and less success in smoking cessation (Anda et al., 1990; Balfour and Ridley, 2000; Kinnunen et al., 1996). Kinnunen and colleagues, looking at data from a randomized interventional trial, found that significantly fewer depressed smokers were able to remain abstinent three months after cessation compared to nondepressed smokers. The same study concluded that depressed patients were more responsive to the use of nicotine for cessation. Investigators have suggested that depressive symptoms may be a part of the withdrawal syndrome in those with a history of depression, presenting an obstacle to successful cessation (Glassman, 1993). It has also been proposed that depression increases the intensity of nicotine dependence (Breslau et al., 1998; Carton et al., 1994). A prospective study by Breslau and colleagues (1998) with a five-year follow-up found that baseline major depression tripled the risk for progression to daily smoking. Smokers with a history of depression or depressive symptoms are thought to “self-medicate” with nicotine and its antidepressant properties (Carton et al., 1994; Lerman et al., 1996). Other studies have hypothesized that smokers are predisposed to develop depression secondary to chronic nicotine central nervous system (CNS) effects. Investigators have suggested that certain genetic or environmental factors may predispose patients to depression and the tendency to smoke independently (reviewed in Breslau et al., 1998).
Weight loss is a commonly cited reason for smoking, especially among young females (reviewed in Perkins, 1993), and fear of weight gain has been an obstacle to successful cessation (Emont and Cummings, 1987; Froom et al., 1998). It has been reported that around 80% of smokers gain weight after cessation (Perkins, 1993). The average weight gain after smoking cessation is 3–4 kg. This weight gain has been found to peak within the first few weeks or months of cessation, and smokers often return to the weight range of nonsmokers. A recent large prospective study, however, found that significant weight gain continued five years after cessation (O’Hara et al., 1998). The amount of weight gain, however, is subject to many individual differences in baseline BMI, age, physical activity, genetic predisposition, and so forth (reviewed in Froom et al., 1998; O’Hara et al., 1998; Pomerleau et al., 2000; Williamson et al., 1991).
The physiologic effect of nicotine has been described as a combination of a reduction in caloric intake and an increase in caloric expenditure. Although the evidence has been inconsistent, short-term increases in intake postcessation occur, peaking within weeks or months (Froom et al., 1998), and decreases in intake upon relapse or initiation have been noted.