It is an unsettled issue in the literature, under which nosological group depersonalization disorder (DPD) should be subsumed.

We measured clinical traits in DPD patients that had previously been implicated in DPD.

Investigated were N = 9 patients with DPD and N = 12 normal controls. To establish the diagnosis of DPD, ICD-10 criteria and cut-off values (CDS > 70) were included. Clinical traits were measured with internationally established psychiatric taxons. Implicit fMRI tasks inducing three steps of happy and sad facial expressions were run, and clinical trait scores were correlated with brain activation in each emotion category.

Significant differences in the regression slopes for the two groups were observed for somatization in the right temporal operculum (happy) and ventral striatum bilaterally (sad). Discriminative regions for depression were the right middle frontal gyrus (happy) and left amygdala (sad). For dissociation, discriminative regions were the left pulvinar (happy) and left parahippocampal gyrus (sad). For state anxiety, discriminative regions were the left ventrolateral prefrontal cortex (happy) and left ventrolateral cortex (sad)(different locations). For trait anxiety, discriminative regions were the right caudate head (happy) and left retrosplenial cortex (sad).

Our results endorse the notion that depersonalization disorder patients show multifaceted clinical traits, but do not justify any bias for a certain nosological category. The differential regions ascertained by regression during emotion processing comparing to normal controls reflect substantial deviations in DPD for clinical trait processing in the brain.