About 5.3 million uninsured adults with mental illness or substance use disorders are eligible for Medicaid coverage under the Affordable Care Act, but about half of them live in states that have not expanded Medicaid under the Act, according to a new report by the Substance Abuse and Mental Health Services Administration. The finding is based on data from the 2009-2013 National Surveys on Drug Use and Health. “One of the primary objectives of the ACA is to protect individuals from large and unexpected out-of-pocket health care expenses,” the report states. “Absent health insurance coverage, these expenses may constitute an important financial barrier to individuals receiving treatment and recovery services.”