Structure of mania: depressive, irritable, and psychotic clusters with different retrospectively-assessed course patterns of illness in randomized clinical trial participants.

BACKGROUND

We investigated the structure of manic episodes by determining whether there was evidence for distinct groups of patients differing in clinical characteristics and course of illness.

METHODS

The subjects were 162 patients hospitalized for manic episodes who underwent comprehensive evaluations of behavior, symptoms, and history before a treatment study. Pretreatment behavior ratings (Schedule for Affective Disorders and Schizophrenia, rated by clinicians, and Affective Disorder Rating Scale, rated by nurses) entered a principal components factor analysis, followed by a cluster analysis of the subjects based on their factor scores. Members of the resulting clusters were compared with respect to clinical characteristics and history of illness.

RESULTS

The six factors were impulsivity, hyperactivity, anxious pessimism, distressed appearance, hostility, and psychosis. The four clusters were characterized as depressive, with high anxious pessimism (n=22), delusional, with high psychosis (n=39), classic (n=72), and irritable, with high distressed appearance and hostility (n=29). Depressive manics had the earliest onset of illness and the highest density of episodes/year, while irritable manics had later onset and the fewest previous episodes.

LIMITATIONS

The number of subjects was smaller than ideal for multivariate analysis, subjects were limited to those able to consent and meet criteria for a randomized clinical trial, and course of illness was determined retrospectively.

CONCLUSIONS

Manic episodes have a dimensional structure but appear to fall naturalistically into types that differ with respect to previous history, symptoms, and clinical characteristics. Whether these are distinct clinical subtypes will require further research.