Covariation among higher-order psychopathology dimensions is driven by nomorbidity and not comorbidity

Abstract Emerging classification frameworks claim that covariation among psychopathology dimensions reflects comorbidity. We scrutinized this claim by applying Bayesian change point models to four waves of the Adolescent Brain Cognitive Development Study data ( N = 11,868 youths; 48% female) and examined associations among higher-order psychopathology dimensions. Covariation between psychopathology dimensions was driven by nomorbidity, not comorbidity: we observed strong positive associations among psychopathology dimensions at relatively extreme low (asymptomatic) levels (for example, when three to five symptoms were endorsed) and weak positive associations at higher levels. For instance, at wave 1, a 1-point increase in internalizing was associated with a 32% increase in externalizing at nearly asymptomatic levels ( B = 0.28), compared with only a 7% increase at higher levels ( B = 0.07). These findings challenge existing assumptions about comorbidity in nonclinical samples, suggesting that covariation is more accurately explained by the absence of symptomatology rather than shared psychiatric conditions.