The proband and sibling sub-samples also had a comparable distribution of lifetime substance dependence disorders—except that more probands reporting opioid dependence histories—with approximately half reporting alcohol or opioid dependence, more than a quarter positive for cannabis dependence, and fewer than 10% positive for dependence on sedatives or stimulants other than cocaine. Cocaine use in the past year by self-report was variable: one third of the sample reported no use; 20% of the sample reported infrequent use, less than once every two weeks on average; 15% of the sample reported using on average approximately once weekly; and a third of the sample reported frequent use, between two times a week on average to several times a day. Thus, about two-thirds of the sample appeared to be in full or partial remission from cocaine dependence, and one-third may still have been cocaine dependent.
