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Digital archive of theses discussed at the University of Pisa


Thesis etd-04072008-150712

Thesis type
Tesi di dottorato di ricerca
Thesis title
Academic discipline
Course of study
Relatore Prof. Cassano, Giovanni Battista
  • depersonalizzazione
  • depressione
  • disturbo bipolare
  • disturbo di panico
Graduation session start date
Release date
Depersonalization and derealization occur on a continuum of situations, from healthy individuals to a severely debilitating disorder where the symptoms can persist chronically and unremittingly for decades. Since 1960s, different neurobiological models have been hypothesized, the majority of them associating depersonalization symptoms with the temporal lobes. Recent advances in the functioning of the limbic system and the application of Geschwind¡¦s concept of disconnection in the corticolimbic networks, pointed out the crucial role of the amygdala and its connections with medial prefrontal cortex and anterior cingulate cortex, the same structures that are strictly interlinked with the neurobiology of emotions and affective disorders.
The detection and measurement of depersonalization remain poorly studied, being most of the rating scales and structured interviews created for a wide range of dissociative symptoms. The Dissociative Experience Scale (DES) represents the self-rating scale with the more extensive literature but the assessment of depersonalization is limited to a subscale of a few items. As far as specific instruments are concerned, the internal consistency is often poor due to the different theoretical approaches to depersonalization during the last thirty years. The Cambridge Depersonalization Scale is probably an exception but demonstrated to be useful mainly in monitoring patients¡¦ response to treatment and the time course of the disease.

The main focus of this thesis is the development and validation of a new clinical instrument for the assessment of depersonalization symptoms: the Structured Clinical Interview for the Depersonalization-Derealization Spectrum (SCI-DER). This instrument is based on a spectrum model that emphasizes soft-signs, sub-threshold syndromes as well as clinical and subsyndromal manifestations. Items of the interview include, in addition to DSM-IV criteria for depersonalization, a number of features derived from clinical experience and from a review of phenomenological descriptions. The SCI-DER includes 49 items exploring ¡§presence¡¨ or ¡§absence¡¨ of lifetime spontaneous symptoms of DP organized into four domains: Derealization, Somatopsychic depersonalization, Autopsychic depersonalization and Affective depersonalization.
Study participants included 300 subjects, in particular 258 consecutive patients with mood and anxiety disorders (7 were also diagnosed depersonalization disorder) and a comparison group of 42 unselected healthy controls enrolled at the same site.
The SCI-DER showed to be acceptable and displayed an excellent internal consistency (0.92), test-retest reliability at 15-20 days (r = 0.88), convergent validity (SCI-DER vs. DES r = 0.74). It significantly discriminated subjects with any diagnosis of mood and anxiety disorders from controls and subjects with depersonalization disorder from controls.

The development and validation of this new instrument has allowed further investigations on specific psychopathological dimensions and their clinical correlates.
Of different components of depression, the ¡§loss of feelings¡¨, or better affective depersonalization, has received less attention in the literature. Nevertheless, its conceptualization and subsequent differentiation from other components, such as anhedonia, may have important implications not only in terms of a better definition of clinical endophenotypes of mood disorders but also because it may allow further studies of the neurobiology of emotional processing. Thus, we tested the hypothesis that anhedonia and affective depersonalization represented two distinct psychopathological dimensions and their clinical correlates were investigated in patients with major depression and bipolar disorder (BD).
Using our data pool of 258 patients with mood and anxiety disorders, classical factor analysis, based on a tetrachoric matrix, was carried out on 16 items: eight were derived from the anhedonia symptoms of the Mood Spectrum Self-Report and eight from the Affective depersonalization domain of the SCI-DER. A two-factor solution was identified, accounting overall for the 52.6% of the variance of the items. Affective Depersonalization was associated with a diagnosis of BD (OR = 1.24; 95%CI = 1.08-1.42; p=0.002) and, in this group of patients, with an early onset of the disease (ƒÒ = -0.342, t = -3.143, p=0.002). Our data suggest that anhedonia and affective depersonalization are two distinct psychopathological dimensions and their clinical correlates bear the opportunity to identify patients with a specific profile for a better clinical and neurobiological definition.

Finally, frequency and clinical correlates of dissociative symptoms, with special attention to depersonalization symptoms were investigated in patients with BD looking specifically at differences between BD-I and BD-II and the comorbidity with panic disorder. The study sample included 91 adult patients with BD (BD-I = 43; BD-II = 48) assessed with the Semi-structured Clinical Interview for Temperament (TEMPS-I), the DES and the SCI-DER. There was no difference in lifetime dissociative experiences or DP symptoms between BD-I and BD-II patients. There was no difference in relation to temperament characteristics. However, lifetime DP symptoms, as assessed with the SCI-DER, were associated to an early onset of the BD (ƒÒ = -0.436, t = -4.572, p<0.001). Derealization symptoms correlated with panic disorder comorbidity (OR = 1.22; 95%CI =1.03-1.46, Wald = 5.177, p=0.023).