Research volunteers who came to the NIDA research facility in Baltimore, Maryland between 1990 and 2007 in response to advertisements and referrals from other research volunteers provided written informed consents, self-reported ethnicity data, drug use histories via the Drug Use Survey and DSMIII-R or IV diagnoses and were reimbursed for their time at different rates during this period (currently about $120 total) as previously described [13], [55], [56]. DNA in 81 pools sampled: a) 400 unrelated European-American “abusers” (mean age and standard deviation = 34 (+/−2), 0.79 male) with heavy lifetime use of illegal substances and, for virtually all, DSMIII-R/IV dependence on at least one illegal abused substance b) 280 “control” European-Americans (mean age 32 (+/−3), 0.6 male) who reported no significant lifetime use of any addictive substance, c) 700 African-American abusers (mean age 34 (+/−3), 0.75 male) and d) 240 African-American controls (mean age 35 (+/−5), 0.43 male) [13], [14], [16]. The modest differences between mean ages of dependent and control individuals would be expected to yield virtually no differences in cumulative lifetime probabilities of developing dependence on one or more illegal substances, based on data from the National Survey of Drug Use in Households (http://oas.samhsa.gov/nsduh/2k7nsduh/2k7Results.cfm#TOC).
