Overview Progesterone and Brain Imaging Study Status: Active, not recruiting Trial end date: 2022-12-01 Target enrollment: Participant gender: Summary Male and female smokers were recruited to undergo 2 phases of smoking cessation. Each phase was 4 days long and involved 3 brain-imaging scans, blood draws and an intervention involving progesterone or a matched placebo. Phase: Phase 4 Details Lead Sponsor: University of PennsylvaniaCollaborator: National Institute on Drug Abuse (NIDA)Treatments: Progesterone