Stress, childhood trauma, and cognitive functions in functional neurologic disorders

Conversion disorder (CD) has traditionally been ascribed to psychologic factors such as trauma, stress, or emotional conflict. Although reference to the psychologic origin of CD has been removed from the criteria list in DSM-5, many theories still incorporate CD as originating from adverse events. This chapter provides a critical review of the literature on stressful life events in CD and discusses current cognitive and neurobiologic models linking psychologic stressors with conversion symptomatology. In addition, we propose a neurobiologic stress model integrating those cognitive models with neuroendocrine stress research and propose that stress and stress-induced changes in hypothalamus-pituitary-adrenal (HPA) axis function may result in cognitive alterations, that in turn contribute to experiencing conversion symptoms. Experimental studies indeed suggest that basal as well as stress-induced changes in HPA axis responding lead to alterations in attentional processing in CD. Although those changes are stronger in traumatized patients, similar patterns have been observed in patients who do not report a history of traumatic events. We conclude that, whereas adverse events may play an important role in many cases of CD, a substantial proportion of patients do not report a history of traumatization or recent stressful events. Studies integrating effects of stress on cognitive functioning in CD are scarce. We propose that, instead of focusing research on defining etiologic events in terms of symptom-eliciting events, future research should work towards an integrated mechanistic account, assessing alterations in cognitive and biologic stress systems in an integrated manner in patients with CD. Such an account may not only serve early symptom detection, it might also provide a starting point for better-targeted interventions.