Clinical Research Directory

Inclusion Criteria: 1. 21 to 60 years old 2. Regular users of inhaled tobacco products (≥5 days out of the last 28) 3. Not planning to quit tobacco use within next month 4. Able to read and write in English Exclusion Criteria: 1. Major neurological conditions or brain trauma 2. Current substance use impairing participation 3. Unstable or significant medical conditions (e.g., COPD, coronary heart disease) 4. Current use of smoking cessation medication (e.g., varenicline, patch) 5. Uncontrolled serious mental illness, suicidality, or inpatient psychiatric hospitalization in the past 6 months 6. Known allergic reaction to ENDS liquids ingredients propylene glycol or vegetable glycerin 7. Unable to use study provided ENDS ad-libitum for at least 3 hours per day 8. Pregnant or breastfeeding as indicated by self-report or urine pregnancy screen MRI-specific exclusion criteria: 1. MRI safety contraindications (e.g., metal implants, claustrophobia) 2. Major neurological conditions or brain trauma