Neurobiological links between dissociation and EMDR

Marco Pagani

Senior Researcher Institute of Cognitive Sciences and Technologies, CNRRome, Italy

Chair of the Neuroimaging Committee of the European Association of Nuclear Medicine

FUNCTIONAL BRAIN

TARGET REGIONS

mPFC modulates emotional response inhibiting amygdala and estinguishing fear response

PREFRONTAL CORTEX

Amygdala is also involved in memory modulation and consolidation

Amygdala has a central role in formation and preservation of emotional memories

AMYGDALA

Lacking inhibitory control from PFC hyperactive amygdala causes excessive firing of cortical and subcortical structures responsible for PTSD symptoms

AMYGDALA

Hippocampus processes episodic and autobiographical memory and is essential in identifying “safe places”

HIPPOCAMPUS

Hippocampus is extremely sensitive to stress and might decrease in volume and neuronal density following chronic cortisol secretion

HIPPOCAMPUS

ANTERIOR AND POSTERIOR CINGULATE CORTEX

ANTERIOR CINGULATE CORTEX

With amygdala and insula modulates mood and anxiety

The tight connections with hippocampus contribute to memory formation

Connectivity with frontal cortex is related to self-esteem and self-evaluation

Anterior cingulate cohordinates hunger and sleep

Posterior cingulate processes the “self” and conscious experiences of emotions and feelings

POSTERIOR CINGULATE CORTEX

With precuneus it is involved in coping with physical threats and processing stressing material

Is relevant in enhancing attention to internal representation of memories of similar experiences

Magnetic resonance exploits magnetic fields to produce anatomical images

It is widespread and relatively cheap

MAGNETIC RESONANCE

STRUCTURAL MAGNETIC RESONANCE

fMRI measures the altered levels of cerebral blood oxygenation. Regional neural activity results in increased local CBF producing an increase in oxyhemoglobin

This leads to a net decrease in de-oxyhaemoglobin and the relative change in concentrations of the two results in a change in signal intensity

Neuronal activity

Blood oxygen level-dependent (BOLD) contrast

fMRI

FUNCTIONAL MAGNETIC RESONANCE

Injected radioisotopes distribute in the brain proportionally to the function to be investigated (blood flow, metabolism or receptor density)

SPECT and PET

EEG

NEUROIMMAGING IN EEG

POST-TRAUMATIC STRESS DISORDER

In DSM-5 PTSD is defined by the coexistence of 4 clusters of symptoms

re-experiencing (intrusive thoughts, flashbacks, nightmares)

avoidance (memory impairment, feelings of detachment, efforts to avoid thoughts, places or people associated with the trauma, social withdrawal)

hyperarousal (abnormal startle responses, hypervigilance, irritability, sleep disturbance, difficulty concentrating)

negative alterations (mood and cognition)

The first neuroimaging studies on PTSD were performed in the USA at military hospitals including mostly Vietnam war veterans

PTSD AND NEUROIMAGING

PTSD AND NEUROIMAGING

STATISTICAL ANALYSES

t-statistics

PCA/ICANetworking

UNIVARIATE

MULTIVARIATE

CONNECTIVITY IN CIVILIAN TRAUMAS

Functional connectivity

Amygdala has strong connections with anterior cingulate, insula and hippocampus

Bremner et al. Current Psychiatry Reports 2002, 4:254–263

Gilboa et al. Biol Psych 2004; 55:263–272

PTSD AND NEUROIMAGING

All neuroimaging studies converge in identifying as implicated in PTSD:

• prefrontal cortex (PFC)• amygdala• hippocampus• insula• Anterior and posterior cingulate cortex

The impairment of PFC associated with a hyper-reactivity of the amygdala constitutes the core neural correlate of PTSD

PTSD AND NEUROIMAGING

NEUROIMAGING and PSYCHOTHERAPY

Neuroimaging techniques have been used in an attempt to shed light on the neurobiological correlates of various psychotherapies revealing their neurobiological effects

Despite positive clinical outcomes functional and neuroanatomical studies are still poorly randomized and insufficient to draw robust conclusions

Peres et al. 2011 – J Psychiatry Research 45:727-734

NEUROIMAGING and PSYCHOTHERAPYETCR - fMRI

NEUROIMAGING and PSYCHOTHERAPYMINDFULNESS

NEUROIMAGING and PSYCHOTHERAPY

EMDR AND SPECT

Bryant et al. 2008; Psychological Medicine 38:555-561

NEUROIMAGING and PSYCHOTHERAPYCBT - fMRI

PTSDNS>S

EMDRR>NR

EMDR AND MRI

Functional and anatomical studies support the evidence of neurobiological models explaining the changes which take place following PTSD-related psychotherapies

These findings call for continued commitment to unravelling the pathophysiological mechanisms underlying these effective treatments of PTSD

NEUROIMAGING and PSYCHOTHERAPY

5 MINUTES FOR QUESTIONS

TIME TO METABOLIZE

AND STRETCHING

Both treatment are effective but EMDR results in a faster disappearance of symptoms

WHY EMDR?

EMDR AND BET

To explore the technical feasibility of the on-line recording of whole EMDR sessions by means of EEG and data analyses

To identify the regions activated during the bilateral ocular stimulation upon traumatic memory exposure

EMDR AND EEG

CLIENTS PRE-EMDR vs non-symptomatic CONTROLS DURING BILATERAL OCULAR STIMULATION

CLIENTS PRE-EMDR vs CLIENTS POST-EMDR NEUROPSYCHOLOGICAL DATA

CLIENTS PRE-EMDR vs CLIENTS POST-EMDR DURING BILATERAL OCULAR STIMULATION

EMDR AND EEG

We monitored by EEG EMDR psychotherapy sessions in two groups of clients

EMDR AND EEG

In the symptomatic phase trauma exposure caused prevalent prefrontal activation

After symptoms disappearance the activation shifted to cognitive associative areas

In chronically exposed clients the neurobiological response was similar to that in healthy controls

The social context impacts on the neurobiological response to trauma exposure

MEMORY MECHANISMS

NEUROIMAGING AND DISSOCIATION

Prefrontal and limbic structures underlie dissociative responses in PTSD.

Differences observed clinically, psychophysiologically, and neurobiologically between patients with dissociative versus non-dissociative responses may suggest different neuronal mechanisms underlying these two distinct reactions.

NEUROIMAGING AND DISSOCIATION

Dissociation is a regulatory strategy invoked to cope with extreme arousal in PTSD, but this strategy appears to function only during conscious processing of threat

Conscious fear Unconscious fear

NEUROIMAGING AND DISSOCIATION

Dissociation correlated positively with activity in the left medial prefrontal and right superior temporal cortices, and negatively with the left superior temporal cortex

NEUROIMAGING AND DISSOCIATION

Dissociative subjects show significant dissociative response including depersonalization and derealization

PTSD AND DISSOCIATION

Dissociative symptoms often occur together with Post-Traumatic Stress Disorder (PTSD)

The role that dissociation plays in the genesis of PTSD and its current taxonomy as an anxiety disorder separate from dissociative disorders has been put into question

Neuroimaging studies have shown a rather heterogeneous pattern of results, by which dissociation might be associated with functional alterations in various areas

Some works have suggested that PTSD subjects can be divided into two subtypes:

subjects who relive their traumatic experiences in form of intensely upsetting recollections and flashbacks, accompanied by an increase in heart rate (hyperarousal subtype, characterized by so-called ‘primary dissociation’)

PTSD AND DISSOCIATION

subjects who show dissociative responses and report experiences such as depersonalization, derealization or ‘zooming out’ phenomena, and do not show any increase in heart rate (dissociative subtype, characterized by so-called ‘secondary dissociation’)

PTSD AND DISSOCIATION

AIMS

The aims of this study were:

to investigate brain structural alteration associated with the presence of dissociative traits along a continuum in a group of traumatized subjects with or without PTSD

to explore the neural correlates associated with different psychological dimensions of dissociation

PTSD AND DISSOCIATION

Thirty-two subjects either developing (N=15) or non-developing (N=17) PTSD underwent MRI and Gray matter volume (GMV) was analyzed

Trait Dissociative Experience Scale (DES), subscales for pathological (DES-T) and non-pathological (DES-A) dissociation, and other clinical measures were assessed

METHODS

PTSD and non-PTSD subjects were compared to evaluate brain alterations related to PTSD pathology

Correlation analyses between dissociation measures and GMV were performed on the whole sample (N=32), irrespective of PTSD diagnosis, to identify alterations related to trait dissociation

PTSD AND DISSOCIATION

RESULTS

Regions in which grey matter volume correlated inversely with PTSD symptoms (in red) and positively (in blue) with overall trait dissociation score

PTSD AND DISSOCIATION

Such increase was mainly due to non-PTSD subjects (green diamonds) in which GMV was strongly positively correlated to trait Dissociation scores

RESULTS

PTSD AND DISSOCIATION

RESULTS

Correlations between GMV and trait, pathological and non-pathological dissociation

PTSD AND DISSOCIATION

Our results indicate that PTSD and trait dissociation are associated with opposite patterns of GMV alterations in medial and lateral prefrontal cortex, where PTSD is associated with a volumetric decrease, while trait dissociation with a volumetric increase.

CONCLUSIONS

The peculiar increase in GMV in lateral PFC in non pathological dissociation might be associated with an enhanced working memory capacities and unconscious suppression of unwanted memories

PTSD AND DISSOCIATION

We have also shown that in sub-clinically dissociated subjects, the tendency to experience pathological dissociative phenomena (i.e., pathological dissociation) and absorption or imaginative involvement (i.e., non-pathological dissociation) widely share the same neural substrates supporting a view of dissociation along a continuum.

CONCLUSIONS

Our results are consistent with previous findings and might underlie the different patterns of emotional modulation (under- vs. overmodulation) and cognitive style (i.e., self-related processing, episodic/autobiographical memory, attention, and working memory) observed in PTSD and dissociation.

We are not claiming that we have solid evidence for all of the links and interpretations in the train of logic presented here

Stickgold, Journal of Clinical Psychology 2002; 58: 61-75

MECHANISM OF ACTIONINTEGRATION OF MEMORIES (Stickgold 2002)

Our goal is to demonstrate that there is a reasonable explanation of our findings which is consonant with modern neurobiology and cognitive neuroscience

THANKSmarco.pagani@istc.cnr.it