شکل روانی و تفکیک شبه جسمی، تجربیات، و احتمال ابتلا فانتزی در اختلالات شبه جسمی

Many studies reported a positive correlation between self-reported traumatic experiences and self-reported dissociative symptoms. Critics postulated that this relation is mediated by the personality trait fantasy proneness. This was confirmed by a number of studies, that mainly used non-clinical samples. The present study was carried out in a clinical sample of patients with somatoform disorders (n = 86). Participants completed the Dissociation Experiences Scale-Revised Edition (DES-II), Somatoform Dissociation Questionnaire (SDQ-20), Traumatic Experiences Checklist (TEC) and Creative Experiences Questionnaire (CEQ). Results show that both psychoform and somatoform dissociation are moderately correlated with traumatic experiences, and that the mediating influence of fantasy proneness on the relation is negligible. It is argued that the mediating role of fantasy proneness found in previous studies may be an artefact of student samples.

The structural dissociation model (Van der Hart, Nijenhuis, & Steele, 2006) postulates a connection between medically unexplained physical symptoms, trauma, and dissociation. Symptoms such as dissociative amnesia, depersonalization, and identity fragmentation are seen as psychoform dissociation, whereas symptoms such as analgesia, anaesthesia, pain, and loss of motor function are referred to as somatoform dissociation ( Nijenhuis, 2000 and Van der Hart et al., 2000). Somatoform dissociative symptoms are held to be physical trauma-related reactions or ‘memories’. Although both types of dissociative symptoms are considered to reflect a similar mental (traumatogenic) etiology, somatoform dissociation (defined by physical symptoms) is held to be phenomenologically distinct from psychoform dissociation (defined by psychic symptoms). The validity of the construct and the alleged traumatogenic etiology of somatoform dissociation are supported by a range of studies, that found associations between somatization and somatoform disorders, psychoform dissociative symptoms, and reported trauma. Several studies suggest that somatoform dissociation, as measured with the Somatoform Dissociation Questionnaire (SDQ-20; Nijenhuis, Spinhoven, Van Dyck, Van der Hart, & Vanderlinden, 1996), is a unique construct, related to but not completely overlapping with psychoform dissociation, and unrelated to general levels of psychopathology ( Nijenhuis, 2000 and Nijenhuis et al., 1999). More in particular, somatoform dissociation has been found associated with reported trauma ( El-Hage et al., 2002, Maaranen et al., 2004, Nijenhuis et al., 1998, Nijenhuis et al., 2004 and Waller et al., 2000), and somatoform symptoms have been found often present in patients that report trauma, and in patients with dissociative disorders ( Darves-Bornoz et al., 1999 and Saxe et al., 1994). Further, in studies on patients with somatoform disorders, it was found that psychoform dissociative symptoms and traumatic events are frequently reported ( Roelofs et al., 2002, Salmon et al., 2003, Spitzer et al., 1999, Tezcan et al., 2003, Van Houdenhove et al., 2001 and Yucel et al., 2002). A crucial question then reads whether the correlations between reported trauma and reported psychoform and somatoform dissociation are due to experienced trauma being causal to dissociation. Some authors argue that a direct and causal connection between experiencing traumatic events and developing (psychoform) dissociative symptoms is evident (e.g. Herman, 1993), but others strongly disagree (e.g. McNally, 2003). Critics stress that the link between trauma and dissociation is mainly correlational, the data stemming from cross-sectional studies that use self-report measures of traumatic experiences and dissociative symptoms ( Merckelbach & Muris, 2001). An exception is a longitudinal follow-up study on dissociation in adolescents who experienced traumatic medical treatment procedures in childhood ( Diseth, 2006). In their review, Merckelbach and Muris (2001) conclude that although clinical studies show substantial correlations between measures of trauma and dissociation, modest associations are typical for college samples. In response, Näring and Nijenhuis (2005) argue that the reported modest magnitudes of the correlations may be due to the use of student samples, that typically score in a restricted range of dissociation and trauma, thus precluding the occurrence of larger associations. According to Merckelbach and Muris (2001), there is also evidence that a third variable, such as family pathology, may serve as a mediating factor in the trauma–dissociation connection (see also Nash, Hulsey, Sexton, Harralson, & Lambert, 1993). Another possible third factor may be attachment disorganization ( Carlson, 1998 and Lyons-Ruth et al., 2006). Last but not least, the Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986), being the most widely used measure of psychoform dissociation, overlaps with personality features such as fantasy proneness, that may compromise the accuracy of retrospective self-reports of traumatic experiences ( Merckelbach & Muris, 2001). Fantasy proneness refers to an individual trait that consists of a deep, profound and long-term involvement in fantasy and imagination, a talent for acting, along with a difficulty to differentiate imagery from real events (Lynn and Rhue, 1988 and Wilson and Barber, 1983). Most fantasy prone individuals are relatively well-adjusted, but report more childhood abuse than low fantasy prone persons (Lynn and Rhue, 1988 and Rhue and Lynn, 1987). Fantasy proneness may either lead to a mix-up of memories that stem from real events with those that stem from fantasies, or it may lead to the adoption of a liberal criterion for reporting past autobiographical events (Merckelbach & Muris, 2001). Possibly then, dissociation and fantasy proneness contribute to increased self-report of traumatic events, so they are not the effect but the cause of (reports of) traumatic events (Merckelbach, Horselenberg, & Schmidt, 2002). In contrast, it has been argued that fantasy proneness may be considered a coping skill for traumatized persons to escape from reality (Näring & Nijenhuis, 2005), consequently leading to the association with trauma and dissociation. A number of studies indeed reported considerable overlap between fantasy proneness and psychoform dissociation. In different student samples, dissociation and fantasy proneness were strongly and positively correlated, ranging from r = 0.47 to r = 0.63 ( Merckelbach and Jelicic, 2004, Merckelbach et al., 2000, Merckelbach et al., 1999 and Merckelbach et al., 2000). Also, positive correlations have been found between fantasy proneness on the one hand, and trauma (r = 0.28; Merckelbach et al., 2002) and negative life events (r = 0.58; Merckelbach, Muris et al., 2000) on the other hand. Interestingly, when the contribution of fantasy proneness was partialled out, the correlation between dissociation and negative life events dropped to practically zero (r = 0.08; Merckelbach, Muris et al., 2000). Not only in student samples, but also in a mixed clinical sample, a positive correlation (r = 0.55) between fantasy proneness and psychoform dissociation has been found ( Merckelbach, à Campo, Hardy, & Giesbrecht, 2005). In sum, the causal relation between childhood trauma and dissociative symptoms is far from established. The personality trait fantasy proneness may have a substantial overlap with dissociation, and may even function as a mediator in the connection between trauma and dissociation. However, the mediating role of fantasy proneness has only been observed in one study, using a student sample (Merckelbach et al., 2002). Other studies only reported an overlap between fantasy proneness and dissociation, or used a measure of negative life events, instead of traumatic experiences, when the contribution of fantasy proneness was tested. Furthermore, only the relation between trauma and psychoform dissociation has been found to be mediated by fantasy proneness. Näring and Nijenhuis (2005) suggest that somatoform dissociation, as measured with the SDQ-20, may be a more reliable indicator of dissociative phenomena than the DES. The present study on psychoform and somatoform dissociation was carried out in a clinical sample of patients with somatoform disorders. It was critically tested whether (1) psychoform and somatoform dissociation are correlated with reported trauma, (2) reported trauma and psychoform and somatoform dissociation are correlated with fantasy proneness, and (3) fantasy proneness functions as a mediator in the anticipated connections between reported trauma and both psychoform and somatoform dissociation.