life-time CIDI diagnosis of MDD]. A supplement was awarded later to enable the project to join the National Institute on Drug Addiction (NIDA) Genetics Consortium and to permit recruitment of never-smokers who did not participate in the laboratory study but were otherwise comparable to the smokers; additional current smokers were also recruited to supplement the core sample of laboratory participants. Efforts were made to keep the cells for nicotine dependence (smokers only), depression and sex approximately equal in size; thus, the sample was not distributed randomly on these variables. For all participants, inclusion and exclusion criteria specified that candidates be between 25 and 65 years old; not be currently pregnant or nursing; have no current or previous diagnosis of psychosis, bipolar disorder, mania or suicide attempts; have no current (<6 months) use of psychoactive medication; have no recent consumption of alcohol beyond specified limits (15 drinks/week for women; 21 drinks per week for men) and have no diagnosis of alcohol abuse or current illegal drug use.
