Imaging IDs Brain Activity Related to Dissociative Symptoms

Trauma-related dissociation consists of several subtypes, with unique brain signatures depending on type of dissociative disorders, new research suggests.

Results from a neuroimaging study showed that different dissociative symptoms were linked to hyperconnectivity within several key regions of the brain, including the central executive, default, and salience networks, and decreased connectivity of the central executive and salience networks with other brain areas.

Depersonalization/derealization showed a different brain signature than partially dissociated intrusions; and participants with posttraumatic stress disorder (PTSD) showed a different brain signature compared with those who had dissociative identity disorder (DID).

“Dissociation is a complex, subjective set of symptoms that are largely experienced internally and, contrary to media portrayal, are not usually overtly observable,” lead author Lauren Lebois, PhD, director of the Dissociative Disorders and Trauma Research Program, McLean Hospital, Belmont, Massachusetts, and assistant professor of psychiatry at Harvard Medical School, told Medscape Medical News.

“However, we have shown that you can objectively measure dissociation and link it to robust brain signatures. We hope these results will encourage clinicians to screen for dissociation and approach reports of these experiences seriously, empathetically, and with awareness that they can be treated effectively,” Lebois said.

The findings were published online October 6 in Neuropsychopharmacology.

Detachment, Discontinuity

Pathological dissociation is “the experience of detachment from or discontinuity in one’s internal experience, sense of self, or surroundings” and is common in the aftermath of trauma, the investigators write.

Previous research into trauma-related pathological dissociation suggests it encompasses a range of experiences or “subtypes,” some of which frequently occur in PTSD and DID.

“Depersonalization and derealization involve feelings of detachment or disconnection from one’s sense of self, body, and environment,” the current researchers write. “Individuals report feeling like their body or surroundings are unreal or like they are in a movie.”

Dissociation also includes “experiences of self-alteration common in DID, in which people lose a sense of agency and ownership over their thoughts, emotions, actions, and body [and] experience some thoughts, emotions, etc as partially dissociated intrusions,” Lebois said.

She added that dissociative symptoms are “common and disabling.” And dissociation and severe dissociative disorders such as DID “remain at best underappreciated and, at worst, frequently go undiagnosed or misdiagnosed,” with a high cost of stigmatization and misunderstanding preventing individuals from accessing effective treatment.

In addition, “given that DID disproportionately affects women, gender disparity is an important issue in this context,” Lebois noted.

Her team was motivated to conduct the study “to learn more about how different types of dissociation manifest in brain activity and to help combat the stigma around dissociation and DID.”

Filling the Gap

The investigators drew on the “Triple Network” model of psychopathology, which “offers an integrative framework based in systems neuroscience for understanding cognitive and affective dysfunction across psychiatric conditions,” they write.

This model “implicates altered intrinsic organization and interactions between three large-scale brain networks across disorders,” they add.

The brain networks included in the study were the right-lateralized central executive network (rCEN), with the lateral frontoparietal brain region; the medial temporal subnetwork of the default network (tDN), with the medial frontoparietal brain region; and the cingulo-opercular subnetwork (cSN), with the midcingulo-insular brain region.

Previous neuroimaging research into dissociative disorders has implicated altered connectivity in these regions. However, although previous studies covered dissociation subtypes, they did not directly compare these subtypes. This study was designed to fill that gap, the investigators note.

They assessed 91 women with and without a history of childhood trauma, current PTSD, and with varying degrees of dissociation.

This included 19 with conventional PTSD (mean age, 33.4 years), 18 with PTSD dissociative subtype (mean age, 29.5 years), 26 with DID (mean age, 37.4 years), and 28 who acted as the healthy controls group (mean age, 32 years).

Participants completed several scales regarding symptoms of PTSD, dissociation, and childhood trauma. They also underwent functional magnetic resonance imaging. Covariates included age, childhood maltreatment, and PTSD severity.

Connectivity Alterations

Results showed the rCEN was “most impacted” by pathological dissociation, with 39 clusters linked to connectivity alterations.

Subtype Connectivity
All 3 networks
  • Within-network hyperconnectivity

  • Decreased connectivity outside rCEN

  • Increased functional connectivity between rCEN and tDN regions and with regions outside the 3 networks

  • Decreased functional connectivity between rCEN and tDN regions and with regions outside the 3 networks

Partially dissociated intrusions
  • Within-network connectivity in lateral orbitofrontal cortex, middle and superior frontal gyrus

  • Increased connectivity between rCEN and tDN regions

  • Decreased connectivity between rCEN and posterior cingulate cortex/precuneus

  • Decreased connectivity between middle temporal gyrus and rCEN

  • Increased connectivity between temporal-parietal-occipital junction and rCEN

Ten clusters within tDN exhibited within-network hyperconnectivity related to dissociation, but only of the depersonalization/derealization subtype.

Eight clusters within cSN were linked to dissociation — specifically, within-network hyperconnectivity and decreased connectivity between regions in rCEN with cSN, with “no significant unique contributions of dissociation subtypes,” the researchers report.

“Depersonalization and derealization symptoms were associated with increased communication between a brain network involved in reasoning, attention, inhibition, and working memory and a brain region implicated in out-of-body experiences. This may, in part, contribute to depersonalization/derealization feelings of detachment, strangeness or unreality experienced with your body and surroundings,” Lebois said.

“In contrast, partially dissociated intrusion symptoms central to DID were linked to increased communication between a brain network involved in autobiographical memory and your sense of self and a brain network involved in reasoning, attention, inhibition, and working memory,” she added.

She noted that this matches how patients with DID describe their mental experiences: as sometimes feeling as if they lost a sense of ownership over their own thoughts and feelings, which can “intrude into their mental landscape.”

In the future, Lebois hopes that “we may be able to monitor dissociative brain signatures during psychotherapy to help assess recovery or relapse, or we could target brain activity directly with neurofeedback or neuromodulatory techniques as a dissociation treatment in and of itself.”

A First Step?

Commenting for Medscape Medical News, Richard Loewenstein, MD, adjunct professor, Department of Psychiatry, University of Maryland School of Medicine, Baltimore, called the paper a “first step in more sophisticated studies of pathological dissociation using cutting-edge concepts of brain connectivity, methodology based on naturalistic, dimensional symptoms categories, and innovative statistical methods.”

Loewenstein, who was not involved with the current study, added that there is an “oversimplified conflation of hallucinations and other symptoms of dissociation with psychosis.” So studies may “incorrectly relate phenomena such as racism-based trauma to psychosis, rather than pathological dissociation and racism-based PTSD,” he said.

He noted that the implications are “profound, as pathological dissociation is not treatable with antipsychotic medications and require treatment with psychotherapy specifically targeting symptoms of pathological dissociation.”

The study was funded by the Julia Kasparian Fund for Neuroscience Research and the National Institute of Mental Health (NIMH). Lebois reported unpaid membership on the Scientific Committee for the International Society for the Study of Trauma and Dissociation, grant support from the NIMH and the Julia Kasparian Fund for Neuroscience Research, and spousal IP payments from Vanderbilt University for technology licensed to Acadia Pharmaceuticals unrelated to the present work. The other investigators’ disclosures are listed in the original paper. Loewenstein has disclosed no relevant financial relationships.

Neuropsychopharmacol. 2022;47:2261-2270. Abstract

Batya Swift Yasgur, MA, LSW, is a freelance writer with a counseling practice in Teaneck, New Jersey. She is a regular contributor to numerous medical publications and is the author of several consumer-oriented health books as well as “Behind the Burqa: Our Lives in Afghanistan” and “How We Escaped to Freedom” (the memoir of two brave Afghan sisters who told her their story).

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