ABSTRACT
Major depressive disorder (MDD) is characterized by depressed mood and/or loss of interest or pleasure in daily activities, as well as the presence of several additional symptoms nearly every day for at least 2 weeks (e.g., feelings of worthlessness, fatigue, difficulty concentrating, psychomotor agitation or retardation, sleep disturbances, changes in appetite or weight, suicidal ideation; American Psychiatric Association, 2013). These changes in mood, thoughts, and behaviors can impair an individual’s ability to function at work or school, in their social relationships, and in other important life domains. In fact, MDD is among the leading causes of disability worldwide (Global Burden of Disease Study, 2016; Vos et al., 2016). The World Mental Health Surveys, conducted by the World Health Organization in 24 countries, found that 4.7% of respondents had MDD in the past 12 months and 11.2% had MDD at some point in their lives (Kessler et al., 2015). In 2017, 7.1% of adults in the United States aged 18 and older (17.3 million adults) had at least one major depressive episode in the previous year (Substance Abuse and Mental Health Services Administration, 2018; National Survey on Drug Use and Health, 2017). Moreover, an estimated 20% of U.S. adults reported at least mild depressive symptoms (Shim, Baltrus, Ye, & Rust, 2011). The high prevalence of clinical depression, in addition to subclinical levels of depressive symptoms, underscores the need for innovative, accessible, and effective strategies for treating depression.
