Neuro-imaging in somatoform disorders: a review.

Somatoform disorder is a subtitle of a main diagnosis included in the Fourth Edition Text Revision of The Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR). The presence of physical signs, which can not be explained by any organic reason based on medical examinations and evaluations, are the basic characteristic of this group of disorders. It is quite common not only in adults, but also in the pediatric population (Kerimoglu and Yalin, 1992; Avci and Arslan, 1995; Akdemir and Unal, 2006). Somatoform disorders, particularly somatization disorder and conversion disorder subtypes, are highly prevalent in the Eastern population, although they are not such common in Western populations (Chandrasekaran et al. 1994). As in other mental disorders, its etiopathogenesis remains unclear; likewise, a combination of psychosocial and biological factors seem to cause the development of this disorder. The psychodynamic approach is the oldest and probably the most appreciable theory among those which have tried to explain the event from a psychosocial aspect. According to this theory, emotional problems are replaced by somatic signs via defense mechanisms including denial, displacement and rationalization; thus, somatic sensations are dealt instead of problems that are difficult to overcome (Yucel and Polat 2007). Again, the signs in this model have sometimes been considered as a way to communicate socially, which are exposed to evade responsibility, to express emotions in another way, and to symbolize emotions and beliefs (Yucel and Polat 2007). The cognitive behavioral approach is another psychosocial model and presents an explanation on a quite distinct basis from that of psychodynamic point of view. The correspondence of the basic A-B-C metaphor of this approach in somatoform disorders is: life events that trigger signs of somatization and accompanying somatic signs and intellectual processes and physical complaints return back as help seeking behaviors depending on the meanings attributed to all of them (Beck 1976). Knowledge concerning the biological basis of somatoform disorders are quite limited (Sagduyu 2001). When comparing somatoform disorders with other mental disorders it is very far behind in terms of neuroscientific data and it can be thought to still be in its infancy. It seems that this results from prejudgement for many years regarding intensive psychosocial, particularly psychodynamic, explanations would be adequate to explain the etiology and that an organic explanation is not necessary; additionally, the disorder is less prevalent in the Western population. Endocrinological studies were the first group of limited neuroscientific studies. Several studies have shown decreased hypothalamo-pituitaryadrenal (HPA) axis activity, which could not be explained medically, in patients with somatic complaints (Ehlert et al. 2001, Parker et al. 2001). Considering increased HPA activity, which is striking in major depressive disorder, this finding claims just the opposite. As evidence about the presence of significant differences in the immune system is increased in patients with somatization syndrome and major depressive disorder, which is directly correlated with HPA axis activity, , the notion aforementioned has been established a more concrete basis (Rief et al. 2001).