Animals responding to stimuli that have previously been paired with nicotine do so more rigorously if they are concurrently exposed to nicotine screening library even noncontingently (Palmatier, Liu, Matteson, Donny, Caggiula et al., 2007). Second, chronic treatment and subsequent withdrawal from nicot
The detrimental effects of cigarettes on the health of individuals and on costs to society are well-documented. Cigarette smoking is the single largest preventable cause of morbidity and mortality in Western countries. Tobacco use negatively impacts the health of every bodily system (USDHHS, 2004) and approximately 440,000 adults in the United States die each year from smoking-related illnesses. The annual economic cost of tobacco use to the United States is $196 billion (CDC, 2008).

Smoking and Depressive Disorders Major Depressive Disorder (MDD) is one of the most common psychiatric illnesses in the United States with a lifetime prevalence of 16.2% and a 12-month prevalence of 5�C9% (Kessler et al., 2003; Pratt & Brody, 2008; Ziedonis et al., 2008). Dysthymia and Minor Depression, like MDD, are also chronic mood disorders that affect a significant number of adults, cause substantial distress and impairment, and have important clinical implications. Dysthymia is defined by a depressed mood experienced for the majority of the time for at least 2 years along with additional symptoms of depression (e.g., sleep disturbance, low energy, low self-esteem; APA, 1994). Dysthymia is associated with significant impairment and a more severe course of later MDD (Keller, 1994; Klein & Santiago, 2003).

Minor Depression, also referred to as subclinical, subthreshhold, or subsyndromal depression (Pincus, Davis, & McQueen, 1999), is included in the DSM-IV-TR (APA, 2002) as a Depressive Disorder Not Otherwise Specified and is defined by the report of symptoms of depression that are fewer in number than those needed for a diagnosis of MDD (APA, 2002). Minor Depression is associated with functional consequences (e.g., work and role impairment) that can equal those experienced with MDD (Ayuso-Mateos, Nuevo, Verdes, Naidoo, & Chatterji, 2010; Howland et al., 2008; Kessler, Zhao, Blazer, & Swartz, 1997; Lewinsohn, Solomon, Seeley, & Zeiss, 2000; Rowe & Rapaport, 2006; Wagner et al., 2000). The lifetime and 12-month prevalence of dysthymia are 6.8% and 1.6�C2.5%, respectively (Ziedonis et al.

, 2008) and the lifetime prevalence of Minor Depression have been estimated to range from 10 to 24% (Judd, Rapaport, Paulus, & Brown, 1994; Kessler et al., 1997; Rowe & Rapaport, 2006). Neurobiological, Batimastat epidemiological, and clinical research all demonstrate significant relationships between smoking and depression (e.g., Mineur & Picciotto, 2010; Picciotto, Addy, Mineur, & Brunzell, 2008; Ziedonis et al., 2008).