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.
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 (ρ = −0.330, P = .001) but not with anhedonia factor scores (ρ = −0.097, P = .361).
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.