Unmet mental health need and subsequent substance use in individuals with a history of depression: Are there differences between metro and nonmetro areas?

Abstract

More than nine million U.S. adults have a co-occurring mental health and substance use disorder. The self-medication hypothesis suggests that individuals with unmet need may alleviate the symptoms of their mental illness by using alcohol or drugs. We examine the relationship between unmet mental health need and subsequent substance use among individuals with a history of depression as well as differences in metro and nonmetro areas. We used repeated cross-sectional data from the National Survey on Drug Use and Health (NSDUH), 2015-2018 after identifying individuals with depression in the past year (n = 12,211). We used logistic regressions with interaction terms to examine the association between unmet need for mental health care and substance use by geographic location. Unmet mental health need was associated with increased use of marijuana (odds ratio [OR] = 1.32, 95% confidence interval [CI]: 1.08-1.64), illicit drugs (OR = 1.75, 95% CI: 1.19-2.58), and prescription drugs (OR = 1.89, 95% CI: 1.19-3.00) among individuals with depression, which did not vary by geographic location. Unmet need was not associated with increased heavy alcohol drinking (OR = 0.87, 95% CI: 0.60-1.26). No differences in substance usage between metro and nonmetro populations were observed for those with an unmet need for mental health care. We found support for the self-medication hypothesis among individuals with depression with respect to alcohol. We examine whether individuals with depression and unmet care needs are more likely to self-medicate with substances including prescription drugs. Due to higher unmeet needs in nonmetro areas, we examine whether the likelihood of self-medication differs in metro and nonmetro areas.