Prevalence of Mental Disorders from Adolescence Through Early Adulthood in American Indian and First Nations Communities

Indigenous communities lack representation in psychiatric epidemiology despite disproportionate exposure to risk factors. We document the cumulative and 12-month prevalence of psychiatric disorders across the early life course among a sample of Indigenous young adults and compare prospective and retrospective reporting of lifetime mental disorders. This community-based participatory research includes data from 735 Indigenous people from 8 reservations/reserves. Personal interviews were conducted between 2002-2010 and 2017-2018 totaling 9 waves; diagnostic assessments of DSM-IV-TR alcohol abuse/dependence, marijuana use/dependence, other substance abuse/dependence, generalized anxiety disorder, major depressive disorder, dysthymic disorder, and attention deficit/hyperactivity disorder occurred at waves 1 (mean age = 11.1 years), 4 (mean age = 14.3 years), 6 (mean age = 16.2 years), 8 (mean age = 18.3 years), and 9 (mean age = 26.3 years). Cumulative lifetime psychiatric disorders reached 77.3% and lifetime comorbidity 56.4% by wave 9. Past-year prevalence and comorbidity at wave 9 were 28.7% and 6.7%, respectively. Substance use disorders (SUDs) were most common with peak past-year prevalence observed when participants were on average 16.3 years old then declining thereafter. Trends in early life course psychiatric disorders in this study with Indigenous participants highlight cultural variations in psychiatric epidemiology including surprisingly low rates of internalizing disorders in the face of risk factors, disproportionately high rates of early-onset and lifetime SUD, and lower rates of past-year SUD in early adulthood compared with prior research.