A. Sample 1) European-American polysubstance abusers and controls. European-Americans volunteered for research at the NIH IRP (NIDA) in Baltimore, Maryland based on word of mouth referrals and newspaper advertisements. Volunteers self-reported their ethnicities, provided drug use histories and provided DSM (diagnostic and statistical manual) diagnoses of substance use disorders [10, 100, 101]. “Abusers” displayed heavy lifetime use of illegal substances [33] and dependence on at least one illegal substance. “Controls” displayed neither abuse nor dependence on any addictive substance and reported no significant lifetime histories of use of any addictive substance. Individuals with intermediate levels of lifetime substance use without dependence were thus not included in analyses of substance dependence, although a number of them were included among samples studied for cognitive abilities (see Samples 15 and 16, below). “Control” individuals thus combined those with no lifetime experience with any addictive substance with those who had modest to moderate exposures to legal addictive substances.
