Phenomenological subtypes of severe bipolar mixed states: a factor analytic study

The correct identification of bipolar mixed states (MS) has important implications for clinical practice. The aim of the study was to define the multidimensional psychopathological structure of severe MS. To our knowledge, no factor analytical studies including only patients with MS, have been conducted before.

In the first week of hospitalization, we evaluated by HAM-D-17, YMRS, BPRS and CGI, 202 Bipolar I inpatients with MS according to DSM-IV criteria referred for an ECT trial. A Principal-component analysis followed by Varimax rotation was performed on the 24-item BPRS. The relationships among different symptomatological subtypes and other clinical characteristics were explored.

Six interpretable factors were extracted: Psychotic-positive symptoms, Mania, Disorientation-Unusual Motor Behaviour, Depression, Negative Symptoms and Anxiety. On the basis of the highest z-scores, we found 6 "dominant" BPRS factor groups, that were statistically distinct and without significant overlap in the main symptomatological presentation. Only 29 (14.4%) of our patients could be described as "Dominant Manic" and 48 (23.8%) as "Dominant Depressive"; most importantly 125 (61.9%) were neither predominately-manic nor predominately-depressive. Variables including age, number of previous episodes, suicidal behavior and HAM-D and YMRS scores significantly differentiated the subtypes.

At least in the most severe forms, MS appears to represent more than the superposition of affective symptoms of opposite polarity. Anxiety, perplexity, psychotic experiences, motor disturbances and grossly disorganized behavior seem to arise from protracted intra-episodic instability and presence of a drive state influencing the mood state and the emotional resonance.