Neurophysiological correlates of dissociative symptoms
- Sylvie J M van der Kruijs1,4,
- Nynke M G Bodde1,
- Evelien Carrette5,
- Richard H C Lazeron1,
- Kristl E J Vonck5,
- Paul A J M Boon1,5,
- Geert R Langereis6,
- Pierre J M Cluitmans1,6,
- Loe M G Feijs6,
- Paul A M Hofman1,2,4,
- Walter H Backes2,4,
- Jacobus F A Jansen2,4,
- A P Aldenkamp1,3,4
- 1Epilepsy Centre Kempenhaeghe, Heeze, The Netherlands
- 2Department of Radiology, Maastricht University Medical Centre, Maastricht, The Netherlands
- 3Department of Neurology, Maastricht University Medical Centre, Maastricht, The Netherlands
- 4School for Mental Health and Neuroscience, Maastricht University, Maastricht, The Netherlands
- 5Reference Centre for Refractory Epilepsy, Ghent University Hospital, Ghent, Belgium
- 6Eindhoven University of Technology, Eindhoven, The Netherlands
- Correspondence to S J M van der Kruijs, Epilepsy Centre Kempenhaeghe, PO Box 61, Heeze 5590AB, The Netherlands;
- Received 5 April 2012
- Revised 23 October 2012
- Accepted 24 October 2012
- Published Online First 22 November 2012
Objective Dissociation is a mental process with psychological and somatoform manifestations, which is closely related to hypnotic suggestibility and essentially shows the ability to obtain distance from reality. An increased tendency to dissociate is a frequently reported characteristic of patients with functional neurological symptoms and syndromes (FNSS), which account for a substantial part of all neurological admissions. This review aims to investigate what heart rate variability (HRV), EEG and neuroimaging data (MRI) reveal about the nature of dissociation and related conditions.
Methods Studies reporting HRV, EEG and neuroimaging data related to hypnosis, dissociation and FNSS were identified by searching the electronic databases Pubmed and ScienceDirect.
Results The majority of the identified studies concerned the physiological characteristics of hypnosis; relatively few investigations on dissociation related FNSS were identified. General findings were increased parasympathetic functioning during hypnosis (as measured by HRV), and lower HRV in patients with FNSS. The large variety of EEG and functional MRI investigations with diverse results challenges definite conclusions, but evidence suggests that subcortical as well as (pre)frontal regions serve emotion regulation in dissociative conditions. Functional connectivity analyses suggest the presence of altered brain networks in patients with FNSS, in which limbic areas have an increased influence on motor preparatory regions.
Conclusions HRV, EEG and (functional) MRI are sensitive methods to detect physiological changes related to dissociation and dissociative disorders such as FNSS, and can possibly provide more information about their aetiology. The use of such measures could eventually provide biomarkers for earlier identification of patients at risk and appropriate treatment of dissociative conditions.