Exposure and the differential response to stressful stimuli affect the development and maintenance of dependence on a number of drugs, including nicotine.1 The important role of stress with respect to risk of nicotine dependence (ND) is evident when one considers the high prevalence of ND in stress-related disorders such as post-traumatic stress disorder (PTSD). Individuals with PTSD are about twice as likely to have ND as those without PTSD.2 Further, smokers with PTSD smoke more cigarettes per day, report experiencing more severe withdrawal symptoms, and have lower quit rates than smokers without PTSD.3, 4 Although the underlying mechanisms that link stress-related disorders to ND have not been fully elucidated, disturbances in stress response and hypothalamic-pituitary-adrenal (HPA) axis activation are the focus of intense research. HPA-axis abnormalities are a hallmark of stress-related disorders such as PTSD,5 and subjects with PTSD responded differently to stressful stimuli compared to subjects unaffected by PTSD.6
