Aims To study cumulative exposure to stressors as a risk factor for drug dependence, and evaluate whether group differences in exposure contribute to differences in prevalence.
Design Cross-sectional community survey of life-time adverse experiences and substance and psychiatric disorders.
Setting Data collected between 1997 and 2000 in Miami–Dade County, USA.
Participants A total of 1803 former Miami–Dade public school students, 93% between ages 19 and 21 years when interviewed. Males and females of Cuban origin, other Caribbean basin Hispanics, African-Americans and non-Hispanic whites are represented equally.
Measurements Drug dependence disorder assessed by DSM-IV criteria using the Composite International Diagnostic Interview, and a 41-item checklist of life-time exposure to major and potentially traumatic experiences. Both measures include age at time of first occurrence.
Findings Life-time rate of drug dependence disorder (total 14.3%) did not vary significantly (P > 0.05) by socio-economic group. Male rate (17.6%) was significantly greater than female rate (10.9%). The African-American rate (6.5%) was dramatically lower than non-Hispanic white (17.0%), Cuban (18.1%) and non-Cuban Hispanic (16.0%) rates despite their dramatically higher exposure to adversity. Twenty-eight of 33 individual adversities were associated with the subsequent onset of drug dependence (P < 0.05). Cumulative life-time exposure was greatest for males and for African-Americans, and was associated inversely with socio-economic level. Multivariate discrete-time event history analysis revealed significant independent effects of distal (>1 year earlier) and proximal (previous year) exposure to adverse events (P < 0.05), controlling for childhood conduct disorder, attention deficit hyperactive disorder and previous psychiatric disorder.
Conclusions Life-time cumulative exposure to distant as well as more recent adversity predicts risk of subsequent drug dependence, although it does not explain ethnic group differences in risk.