Distinguishing affective depersonalization from anhedonia in major depression and bipolar disorder.

BACKGROUND Affective depersonalization has received limited attention in the literature, although its conceptualization may have implications in terms of identification of clinical endophenotypes of mood disorders. Thus, this study aims to test the hypothesis that anhedonia and affective depersonalization represent 2 distinct psychopathological dimensions and to investigate their clinical correlates in patients with major depressive disorder (MDD) and bipolar disorder (BD). METHODS Using a data pool of 258 patients with mood and anxiety disorders, an item response theory-based factor analysis approach was carried out on 16 items derived from 2 clinical instruments developed in the Spectrum Project (the Structured Clinical Interview for Mood Spectrum and the Structured Clinical Interview for Derealization-Depersonalization Spectrum). Clinical correlates of these psychometrically derived dimensions were subsequently investigated in patients with BD or MDD. RESULTS Using an item response theory-based factor analysis, a 2-factor solution was identified, accounting overall for the 47.0% of the variance. Patients with BD showed statistically significant higher affective depersonalization factor scores than those with MDD (Z = 2.215, P = .027), whereas there was no between-groups difference in anhedonia scores (Z = 0.825 P = .411). In patients with BD, age of onset of the disease correlated with affective depersonalization factor scores (rho = -0.330, P = .001) but not with anhedonia factor scores (rho = -0.097, P = .361). CONCLUSIONS Affective depersonalization and anhedonia seem to be 2 distinct psychopathological dimensions, although closely related, bearing the opportunity to identify patients with a specific profile for a better clinical and neurobiological definition.