Differentiation of bipolar I and II disorders by examining for differences in severity of manic/hypomanic symptoms and the presence or absence of psychosis during that phase

Background: DSM-IV criteria for mania/hypomania overlap considerably. We sought to examine the utility of a model differentiating bipolar I and II disorders by weighting the presence or absence of psychosis during manic/hypomanic episodes as opposed to simply weighting symptom severity. Methods: A set of 632 patients with a so-assigned clinical bipolar l or II disorder diagnosis contributed to the principal analyses, and a subset of 210 was included in a comparative analyses of DSM-assigned diagnoses. We also examined the impact of duration of highs on symptom patterns and the extent to which depressive episodes were psychotic or non-psychotic melancholic in type. Results: There were no group differences for bipolar I and II patients (clinical or DSM groups) by age, gender, age of onset or age of formal bipolar diagnosis. Clinically assigned bipolar l patients returned higher severity scores than bipolar II patients on manic/hypomanic symptoms, but such differentiation was limited. Clinically-assigned bipolar l patients were more likely than bipolar II patients to be diagnosed with psychotic depression, and had lower rates of non-melancholic depression. Duration of highs had some impact on the phenomenology of highs, but not on the phenomenology of depression. Limitations: We cannot establish the degree to which clinicians validly differentiated those with bipolar disorder, and accurately judged the lifetime presence of psychotic features and of depressive subtype differentiation. Conclusions: Findings support the utility of an alternative model to DSM-IV in weighting the respective presence or absence of psychotic symptoms during highs in differentiating bipolar I and II disorders. (C) 2013 Elsevier B.V. All rights reserved.