Abstract
Depressive and anxiety disorders are highly comorbid, which has been theorized to be due to an underlying internalizing vulnerability. We aimed to identify groups of participants with differing vulnerabilities by examining the course of internalizing psychopathology up to age 45. We used data from 24158 participants (aged 45+) in 23 population-based cross-sectional World Mental Health Surveys. Internalizing disorders were assessed with the Composite International Diagnostic Interview (CIDI). We applied latent class growth analysis (LCGA) and investigated the characteristics of identified classes using logistic or linear regression. The best-fitting LCGA solution identified eight classes: a healthy class (81.9%), three childhood-onset classes with mild (3.7%), moderate (2.0%), or severe (1.1%) internalizing comorbidity, two puberty-onset classes with mild (4.0%) or moderate (1.4%) comorbidity, and two adult-onset classes with mild comorbidity (2.7% and 3.2%). The childhood-onset severe class had particularly unfavorable sociodemographic outcomes compared to the healthy class, with increased risks of being never or previously married (OR = 2.2 and 2.0, p < 0.001), not being employed (OR = 3.5, p < 0.001), and having a low/low-average income (OR = 2.2, p < 0.001). Moderate or severe (v. mild) comorbidity was associated with 12-month internalizing disorders (OR = 1.9 and 4.8, p < 0.001), disability (B = 1.1-2.3, p < 0.001), and suicidal ideation (OR = 4.2, p < 0.001 for severe comorbidity only). Adult (v. childhood) onset was associated with lower rates of 12-month internalizing disorders (OR = 0.2, p < 0.001). We identified eight transdiagnostic trajectories of internalizing psychopathology. Unfavorable outcomes were concentrated in the 1% of participants with childhood onset and severe comorbidity. Early identification of this group may offer opportunities for preventive interventions.
Highlights
Depressive and anxiety disorders are responsible for the largest share of the global burden of disease due to mental disorders (Kassebaum et al, 2016), as a consequence of their high prevalence, early age-of-onset (AOO), and chronic/recurrent course (Bruce et al, 2005; Judd et al, 1998; Kessler et al, 2005a; Penninx et al, 2011; Wardenaar, Conradi, & de Jonge, 2014)
The current analysis focuses on all respondents (n = 24.158) who were 45 years or older at the time of the interview and were interviewed about all relevant internalizing disorders
The three childhood-onset classes were characterized by the early onset of specific phobia; moderate and severe childhood-onset classes showed high rates of early-onset social anxiety disorder and often developed major depressive disorder (MDD) or other internalizing disorders later in life
Summary
Depressive and anxiety disorders are responsible for the largest share of the global burden of disease due to mental disorders (Kassebaum et al, 2016), as a consequence of their high prevalence, early age-of-onset (AOO), and chronic/recurrent course (Bruce et al, 2005; Judd et al, 1998; Kessler et al, 2005a; Penninx et al, 2011; Wardenaar, Conradi, & de Jonge, 2014). Factor analyses aimed at identifying an evidence-based structure of psychopathology have found that depressive and anxiety disorders cluster together in an internalizing dimension, while substance use disorders and behavioral disorders cluster together in an externalizing dimension (Krueger et al, 2018) These dimensions have been found to explain almost all of the comorbidity between specific disorders (Kessler et al, 2011).
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