Where is mania in the meta-structure of psychopathology?

Background. The nosology of mania has long been a conundrum. Prior studies have alternately concluded that it is an internalizing disorder, a thought disorder, or a unique condition. Unfortunately, nearly all existing studies assessed symptoms cross-sectionally. This is problematic for syndromes that follow a more episodic course, such as mania. Here, we test whether including a history of episodes, not simply current symptoms, can help resolve the placement of mania in the meta-structure of psychopathology. Methods. First-admission patients with psychosis from the Suffolk County Mental Health Project (N = 337) were followed across 20 years. Internalizing, thought disorder, and mania symptoms were assessed at year 20, whereas corresponding episodes (i.e. depressive, psychotic, and manic) were assessed across three intervals spanning the previous 20 years. We tested five models to determine whether mania (current and past) loaded onto the internalizing factor, the thought disorder factor, or an independent factor. A final model was validated against established markers of bipolar disorder. Results. For depression and psychosis, current and past markers were congruent in loading onto internalizing and thought disorder factors, respectively. However, current and past markers of mania diverged: current mania was most strongly related to the thought disorder dimension, whereas past mania formed an independent factor. Classic correlates of mania – including family history, genetic risk, and neuropsychological function – were associated only with the history of mania dimension. Conclusions. Including illness course in structural models of psychopathology suggests that mania is distinguished from internalizing and thought disorder factors, whereas assessments of current symptoms place it with psychosis. These findings require independent validation, but if replicated, they would support a separate spectrum of mania defined by the occurrence of episodes across the lifetime.