Investigation of Nicotine Seeking Behavior in Current Smokers

Non-treatment-seeking cigarette smoking individuals were recruited from the Detroit, MI area. Individuals were screened for cardiovascular, neurological, and psychiatric contraindications. 21 healthy smokers completed two oral pre-treatment experimental sessions (on separate non-consecutive days) in randomized order under double-blind conditions: placebo (lactose) and stress (54mg yohimbine and 10mg hydrocortisone). Yohimbine + hydrocortisone elicit a neurochemical and physiological response that mimics a 'natural' stressor. Placebo and stress sessions were identical and started at 11am. Upon arrival, subject sobriety was confirmed with expired breath alcohol measurement (\<.02%). At 11:30am, each subject smoked 6 cigarette puffs (preferred brand; provided by study) over 5 minutes to control for recent nicotine exposure. Throughout each experimental session, subjects periodically completed self-reported measures of cigarette craving, nicotine withdrawal symptoms, affect, and anxiety, and vital signs were measured. Subjects self-administered (swallowed) oral doses of yohimbine (or placebo) at 11:45am and hydrocortisone (or placebo) at 12:15pm. At 1pm, subjects completed a 60-min neuroimaging scan which included: 1) T1-weighted structural scan, 2) proton functional magnetic resonance spectroscopy (fMRS) acquisition from the left prefrontal cortex during a letter 2-back working memory paradigm, and 3) functional magnetic resonance imaging (fMRI) acquisition during an N-back paradigm yoked with cigarette cues. At 2:30pm, subjects completed an 11-trial choice progressive ratio task in which they could earn cigarette puffs (preferred brand; provided by study) or money. At 3pm, subjects self-administered earned cigarette puffs (video monitored). Subjects remained on site until 4pm discharge.