The COGEND replication sample of young adult daily smokers consisted of 335 European Americans with an average age at interview of 28 and the majority were female (61%). Among COGEND young adult daily smokers, 50% were nicotine dependent, 24% smoked within 5 minutes after waking, 25% smoked greater than 20 cigarettes per day, and 31% were slow metabolizers (distribution in Figure S1).
