Emergence of recreational drug abuse as a major risk factor for stroke in young adults OBJECTIVE: To investigate the clinical and epidemiologic relations between recreational drug abuse and stroke in young persons. DESIGN: A case-control study based on medical records. SETTING: San Francisco General Hospital, a 400-bed municipal hospital. PATIENTS: Consecutive sample of 214 patients aged 15 to 44 years, admitted between 1979 and 1988 with a diagnosis of ischemic or hemorrhagic stroke. An equal number of control patients admitted with diagnoses of status asthmaticus, acute appendicitis, or acute cholecystitis were matched to stroke patients by age, sex, and year of hospitalization. MEASUREMENTS AND MAIN RESULTS: Seventy-three patients with stroke (34%) were drug abusers compared with 18 (8%) of the controls. In 47 patients with stroke, temporal proximity of drug administration (n = 34) or infectious endocarditis (n = 13) suggested a direct association between drug abuse and stroke. After controlling for other identifiable stroke risk factors, the estimated relative risk for stroke among drug abusers compared with that among non-drug abusers was 6.5 (95% CI, 3.1 to 13.6), and this increased to 49.4 (CI, 6.4 to 379.0) for those patients whose symptoms began within 6 hours of drug administration. Among patients less than 35 years of age, drug abuse was the most commonly identified potential predisposing condition (47%), and it was the only condition with a significantly elevated relative risk for stroke (11.7; CI, 3.2 to 42.5). Further, a substantial rise in the proportion of drug-related strokes was observed in the last 3 years of the study (31% in 1986 to 1988, compared with 15% in 1979 to 1985, P = 0.008). Cocaine, especially recently, was the drug used most frequently in drug-related strokes. CONCLUSION: In an urban population such as ours, recreational drug abuse appears to be a prominent and growing risk factor for strokes in young adults. 