Background: The aim of this study was to extend our knowledge of associations among the constructs of alexithymia, depression, somatization and dissociation. Sampling and Methods: 924 nonclinical subjects answered questions about depression (21-item Beck Depression Inventory), somatization (13-item somatization part of Symptom Check List-90), dissociation (28-item Dissociative Experiences Scale) and alexithymia (20-item Toronto Alexithymia Scale). In addition, a 12-item General Health Questionnaire (GHQ-12) was administered to detect psychiatric distress among subjects. Results: The results suggested that there was a significant clinical correlation between somatization, dissociation, depression and alexithymia (rho varied from 0.31 to 0.56). The principal component analysis revealed the presence of four components: depression, somatization, dissociation and alexithymia. The use of factor scores diminished the covariance between measures (rho varied from –0.10 to 0.01 between the factor scores). There was almost no correlation between the dissociation factor (rho = 0.06) and alexithymia factor (rho = 0.09) scores and general distress (GHQ-12). Conclusions: This study suggests that while somatization, dissociation, depression and alexithymia are distinct constructs, they correlate to a considerable extent. The use of factor analysis and factor scores should be considered to diminish covariance between the above constructs. Comparing results between factored and unfactored results may prove illuminating. As a case in point, the results suggest that the part of dissociation that coincides with other constructs (overlaps) is associated with distress, whereas the distinct part of dissociation (no shared covariance) is not associated with distress. The same applies to the alexithymia construct. Longitudinal studies are needed to show whether there is a trait such as a relatively stable dissociation component and also whether a separate state-dependent dissociation component exists that is associated with coincident distress, somatization and depression.

The aim was to determine the rate of dissociative disorders among psychiatric in- (n = 34) and out-patients (n = 37) and to compare the rate to that of nonclinical subjects (n = 297). Dissociative disorders (17% of patients) could be grouped according to the severity of the symptoms and their relation to affective disorders.

The confirmatory factor structure of the Finnish version of the Dissociative Experiences Scale II (DES-II) was exactly the same in the non-clinical population (n=924) as was found in the most recent study in the USA (with the original English version) and as suggested by the authors of the original version. The Finnish version of the DES-II has a Cronbach's alpha of 0.92, and there is a clear positive correlation (from 0.31 to 0.66) between all 28 items and the total score (P<0.001 for all items), indicating good internal consistency and reliability. We also investigated dissociative experiences and psychiatric distress with the DES-II and the General Health Questionnaire (GHQ-12). The increased proportion of "pathological dissociation" (DES-T) to "non-pathological dissociation" (DES-NP) was directly linked with increased distress. This finding is meaningful for the debate on the utility of the different DES-II scoring systems.

Handedness is considered an indirect marker for bilateral language capacity in the brain. The Edinburgh Inventory for Handedness and the Dissociative Experiences Scale (DES) were administered to 297 nonclinical volunteers. Female sex, young age, and non-right handedness accounted for 24% of the total variance on the DES, including both pathological and nonpathological dissociative experiences. This is consistent with the hypothesis that cerebral lateralization indicating handedness is a predisposing factor for dissociative episodes especially in female subjects.

Visual distortions may be a frightening experience. They are often incorrectly diagnosed and easily dismissed. The causes of visual distortions are poorly understood. The aim of this study was to investigate the link between visual distortions and dissociative experiences in a nonclinical population. A total of 297 nonclinical volunteers completed the Dissociative Experience Scale and answered questions concerning visual distortions. Our study suggests that visual distortions are quite common and that there is a clear link between visual distortions and dissociative phenomena. Literature indicates that this may be caused by disturbances in brain lateralization. Bilateral language capacity may interfere with abilities usually associated with the nondominant hemisphere. Research efforts attempting to shed light on the above matter may benefit our knowledge for dissociative phenomena. An interdisciplinary approach is needed.