Stimulant dependence and stimulant-associated psychosis: clinical characteristics and age of onset in a native American community sample.

OBJECTIVES

Native Americans experience some of the highest rates of Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) stimulant dependence (SD) of all US ethnic groups. The present report examined the clinical characteristics and age of onset of stimulant use, SD, remission from SD, and stimulant-associated psychosis (SAP) in a Native American community sample.

METHODS

Demographic information, stimulant (methamphetamine or cocaine) use, and lifetime Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) psychiatric disorder diagnoses were assessed in 858 Native Americans. Logistic regression was used to assess the associations of demographic, stimulant use, and psychiatric disorder variables with SD, remission from SD, and SAP. Kaplan-Meier survival analyses were used to assess time from first use to the onset of SD.

RESULTS

The overall rate of SD was 33%, of remission from SD 73%, and of SAP 17%. Stimulant dependence was associated with older age, less current annual household income, fewer lifetime years of education, intravenous stimulant use, and earlier age of first stimulant use. Remission from SD was associated with older age, currently being married, and never having used stimulants intravenously. Attention-deficit/hyperactivity disorder (assessed as a lifetime disorder), increased number of years of daily stimulant use, and intravenous use were independently associated with SAP. Younger age at first use was significantly associated with shorter survival to the onset of SD.

CONCLUSIONS

Stimulant dependence is prevalent in this population and is associated with less income and education and an earlier age at first use. Intravenous stimulant use adds additional risk for SD, nonremission, and psychosis.