Salivary stress biomarkers of recent nicotine use and dependence.

BACKGROUND: Although stress plays a critical role in vulnerability to nicotine use and dependence, the stress response factors that contribute to smoking behaviors remain poorly elucidated. To minimize the confounding effects of chronic nicotine use, assessing individuals with relatively short smoking histories is critical for characterizing the neurobiological substrates associated with nicotine dependence early in the course of illness. OBJECTIVES: This pilot study examined sympathetic nervous system (alpha-amylase) and hypothalamic-pituitary-adrenal axis (cortisol, dehydroepiandrosterone) responses to the Trier Social Stress Test (TSST) in young adult smokers. Associations among objective indices of recent smoking (salivary cotinine, carbon monoxide in the breath [CO]), behavioral measures of nicotine dependence and withdrawal, and salivary biomarkers in response to the TSST were investigated. METHODS: Smokers (N = 64; 28 males, 36 females) provided saliva samples at 30 min intervals for 2 h prior to the TSST and every 10 min for 1 h following the TSST. RESULTS: Alpha-amylase responses to the TSST were positively associated with salivary cotinine levels but negatively associated with CO levels. Individuals with a lower level of nicotine dependence had increased cortisol responses to the stressor, whereas those with a higher level of nicotine dependence did not show any cortisol changes in response to the stressor. CONCLUSIONS: These findings indicate that different mechanisms may be involved at different levels of nicotine dependence severity. Recent nicotine use and lower dependence severity may be associated with increased activation of the stress response systems. In contrast, more severe levels of dependence may downregulate stress response systems.