Latent Classes of Comorbid Substance Use and Internalizing and Externalizing Symptoms and Their Stability in U.S. Adults Over Time: Findings from the PATH Study Waves 1-3 (2013-2016).

The co-occurrence of mental disorder symptoms is common in people who use substances. It is unclear whether patterns of comorbidity in a population-based sample of adults are consistent with prior work. The study goal was to identify this comorbidity structure and evaluate its stability over time. Using Waves 1, 2, and 3 of the Population Assessment of Tobacco and Health Study, this study applied latent class analysis to identify comorbid substance use, internalizing and externalizing mental disorder symptoms, and their stability over time. A four-class solution was identified for Wave 1 as: (1) low symptom (N = 23,571, 72.9%), (2) internalizing (N = 4,098, 12.7%), (3) externalizing (N = 2,691, 8.3%), and (4) comorbid (N = 1,960, 6.1%). Similar latent profiles emerged across the three waves specifically where the low symptom class was largest (65.5% to 72.9%), and the comorbid class was smallest (6.1% to 8.2%). However, the composition of the classes changed in Wave 3 with low comorbid (N = 5,400, 20.6%) and substance use (N = 1,524, 5.8%) classes emerging. Overall, when individuals transitioned from preceding to subsequent wave, they typically transitioned into the low symptom class. The comorbidity structure of substance use behaviors, including cigarette and e-cigarette use, and mental disorder symptoms in a population-based sample of U.S. adults was characterized by four classes. Psychiatric comorbidity may vary in severity within a population and by specific sociodemographic factors. When comparing the latent classes over three years of data, the results suggest that the comorbidity structure may change as participants age.