Biopsychological trait markers supporting the stress-diathesis model in functional neurological disorders. (S51.010)

Abstract

<h3>Objective:</h3> To shed light on the underlying neurobiological mechanisms of functional neurological disorders (FND), we analysed the relationship between potential dysregulation of the Hypothalamic-Pituitary Adrenal (HPA) axis, trauma history, and structural brain abnormalities. <h3>Background:</h3> Stress is a well-known risk factor to develop FND. Only little is known about the biological stress regulation, and what might be the role of predisposing biological and psychosocial risk factors. <h3>Design/Methods:</h3> We set out to study the HPA axis analysing the cortisol awakening response and diurnal baseline cortisol in 86 patients with mixed functional neurological symptoms compared to 76 healthy controls. We then examined the association between cortisol regulation and severity and duration of traumatic life events. Finally, we analysed volumetric brain alterations in brain regions particularly sensitive to psychosocial stress, acting on the assumption of the neurotoxic effect of prolonged cortisol exposure. <h3>Results:</h3> Overall, patients had a significantly flatter cortisol awakening response (<i>P</i> &lt; 0.001) and reported longer (<i>P</i> = 0.01) and more severe (<i>P</i> &lt; 0.001) emotional neglect as compared to heathy controls. Moreover, volumes of bilateral hippocampus and amygdala were found to be reduced in patients. Using a partial least squares correlation, we found that in patients, emotional neglect plays a role in the multivariate pattern between trauma history and HPA axis dysfunction, whilst cortisol did not relate to reduced brain volumes. <h3>Conclusions:</h3> In summary, this study supports a stress-diathesis model for FND and showed an association between different attributes of trauma history and abnormalities in HPA-axis function. Moreover, we suggest that reduced hippocampal- and amygdalar volumes represent a biological ‘trait marker’ for FND patients, which might contribute to a reduced resilience to stress. <b>Disclosure:</b> Mrs. Weber has nothing to disclose. Mrs. Bühler has nothing to disclose. Mr. Loukas has nothing to disclose. Dr. Aybek has received personal compensation in the range of $500-$4,999 for serving as an officer or member of the Board of Directors for Swiss Movement Disorder Foundation. The institution of Dr. Aybek has received research support from Swiss National Science Foundation.