[Study of dissociative disorders and depersonalization in a sample of young adult French population].
Questioned by several researches about dissociative disorders, the authors study differences established on the nosographic register, through a quantitative study and a psychodynamic argumentation in a sample of french population. From the utilisation of the Dissociative Experiences Scale (DES) created by Bernstein E and Putnam FW (1986), which is an excellent screening tool for dissociative disorders and constructed on DSM II diagnostic criterions, the authors will show the interest of a psychodynamic analysis of dissociative disorders, in the face of the diagnostic difficulty in relation to several approaches of this concept. This difficulty is studied giving the background to dissociative disorders and depersonalization. Ionescu (1999) shows that between 1890 and 1910 dissociation represents one of major themes of psychology, psychopathology and psychiatry. Then, this interest about dissociation decreases and will be almost non-existent in the middle of the twentieth century. The interest for dissociative disorder will grow in the eighties with north-american studies about multiple personality disorders. Until 1980, dissociative disorders exist in DSM II as a list of symptoms included into hysterical neurosis, among the conversive disorders. In 1980, the publication of DSM III replaces the notion of hysteria with the notion of dissociative disorder. In this way, we can see on the one hand somatoform disorders quarterly corresponding to the ancient version of conversive hysteria, and on the other hand dissociative disorders characterized by a perturbation of consciousness, memory, identity or perception of environment. In 1994, The DSM IV delete the notion of hysteria and neurosis and keeps only the notion of dissociative disorders. They include now the five following categories: dissociative amnesia, dissociative fugue, depersonalization disorder, dissociative identity disorder, dissociative disorder not otherwise specified (including derealization). Depersonalization disorders consist of "persistent or recurrent episodes of depersonalization characterized by a feeling of detachment or estrangement from one's self. The individual may feel like an automation or like he or she is living in a dream or movie" (DSM IV). Depersonalization disorder cannot be diagnosed if it is part of schizophrenia, panic disorder, acute stress disorder or dissociative identity disorder. Various depressive disorders, hypocondriasis or obsessive-compulsive disorders can accompany depersonalization disorder. The first purpose of this study will search the frequency of dissociative disorders and depersonalization in a sample of normal population. Further, the inclusion of depersonalization amongst dissociative disorders seems not so evident: depersonalization belongs to self-consciousness disorder in french psychiatry. This fact seems more logical insofar as dissociative disorders have all together a memory and consciousness perturbation, and this perturbation is missing from depersonalization's feeling. The second purpose will be to clarify and specify the particularity of depersonalization among dissociative diorders, from the psychopathological point of view.


METHODS
The sample (n = 248) is made up of french young adults aged 17 to 30 (mean age = 20, SD = 15 and 24% is male population). Subjects were streamming from universities. The screening tool which was used is the Dissociative Experiences Scale, a 28-item patient questionnaire regarding various dissociative symptoms. The subject is asked to indicate the percentage of time, to the nearest 5%, that particular symptom is experienced. The score is made by adding the various percentages and finding a mean that is expressed in numbers from 0 to 100. Normal scores are in the range of 5 to 15 in american adults.


RESULTS
The utilization of principal component analysis (PCA) with varimax rotation is justified by the will to compare this study with American's studies. The mean score obtained is 17.44%, and 13.3% of the scores exceed a psychiatric threshold at 30%. The descriptive analysis shows that the component 1 (PCA without varimax rotation) represents 33.02% of total explained variance. This result demonstrates that the structure of the DES is based on one concept, the same as the american population, it is the concept of dissociation. The Principal Component Analysis with varimax rotation of the DES ratings yielded a tree-factor solution: imaginative absorption (F1), depersonalization-derealization (F2) and dissociative amnesia (F3). Mean score for each factor is respectively: F1 = 21.56%, F2 = 13.95%, F3 = 11.04%. DES reliability was studied through computation of Cronbach's coefficient (0.92). The PCA with varimax rotation brings to the fore a full dissociative disorder without any trouble of memory and consciousness. This fact questions again once more the link between hysteria and dissociative disorders. There is here a clinical distinction between depersonalization-derealization and other dissociative disorders. Indeed, the absence of significant alteration of memory and conscience is specific of depersonalization and derealization in this study.


CONCLUSIONS
Finally, this study concurs with DSM IV dissociative criterions. At last, one factor of PCA is composed by the association of depersonalization and derealization, in contradiction with DSM IV definition. This result shows that, into the french population, we cannot divide the two concepts.
Moyano
O
O
Centre de Recherches en Psychopathologie et Psychologie Cliniques, Université Lumière Lyon 2.
Claudon
P
P
Colin
V
V
Svatos
J
J
Thiébaut
E
E
D000328:Adult; D003861:Depersonalization / Q000175:diagnosis / Q000453:epidemiology*; D004213:Dissociative Disorders / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires