Paul A Frewen

The University of Western Ontario | UWO · Department of Psychiatry

Collective research has identified a key electroencephalogram (EEG) signature in patients with posttraumatic stress disorder (PTSD), consisting of abnormally reduced alpha (8-12 Hz) rhythms. We conducted a 20-session, double-blind, randomized controlled trial of alpha-desynchronizing neurofeedback in patients with PTSD over 20-weeks. Our objective...

Collective research has identified a key electroencephalogram (EEG) signature in patients with posttraumatic stress disorder (PTSD), consisting of abnormally reduced alpha (8-12 Hz) rhythms. We conducted a 20-session, double-blind, randomized controlled trial of alpha-desynchronizing neurofeedback in patients with PTSD over 20-weeks. Our objective...

Background: Alterations within large-scale brain networks-namely, the default mode (DMN) and salience networks (SN)-are present among individuals with posttraumatic stress disorder (PTSD). Previous real-time functional magnetic resonance imaging (fMRI) and electroencephalography neurofeedback studies suggest that regulating posterior cingulate cor...

The human brain engages the sense of self through both semantic and somatic self-referential processing (SRP). Alpha and theta oscillations have been found to underlie SRP but have not been compared with respect to semantic and somatic SRP. We recorded electroencephalography (EEG) from 50 participants during focused internal attention on life roles...

Background: In 2012, a dissociative subtype of post-traumatic stress disorder (PTSD) was introduced into the DSM based on emerging clinical and neurobiological evidence of a distinct PTSD phenotype characterized by trauma-related dissociation. Ten years later, considerable research has demonstrated unique small-scale (i.e., node-based) and large-sc...

We present here a unifying framework for affective phenomena: the Human Affectome. By synthesizing a large body of literature, we have converged on definitions that disambiguate the commonly used terms—affect, feeling, emotion, and mood. Based on this definitional foundation, and under the premise that affective states reflect allostatic concerns,...

The 4-dimensional (4-D) model of trauma-related dissociation differentiates between dissociative experiences involving trauma-related altered states of consciousness and symptoms of distress that do not appear to involve alterations in normal waking consciousness across four phenomenological dimensions (i.e., our experience of time, thought, body,...

Background Intrinsic connectivity networks, including the default mode network (DMN), are frequently disrupted in individuals with posttraumatic stress disorder (PTSD). The posterior cingulate cortex (PCC) is the main hub of the posterior DMN, where the therapeutic regulation of this region with real-time fMRI neurofeedback (NFB) has yet to be expl...

Background: Potentially traumatic stressors can lead to various transdiagnostic outcomes beyond PTSD alone but no brief screening tools exist for measuring posttraumatic responses in a transdiagnostic manner. Objective: Assess the psychometric characteristics of a new 22-item transdiagnostic screening measure, the Global Psychotrauma Screen (GPS)....

Systematic reviews of neuroimaging studies confirm stimulus-induced activity in response to verbal and non-verbal self-referential processing (SRP) in cortical midline structures, temporoparietal cortex and insula. Whether SRP can be causally modulated by way of non-invasive brain stimulation (NIBS) has also been investigated in several studies. He...

Objectives The need for remote delivery of mental health interventions including instruction in meditation has become paramount in the wake of the current global pandemic. However, the support one may usually feel within the physical presence of an instructor may be weakened when interventions are delivered remotely, potentially impacting one’s med...

Background: Child maltreatment is embedded in a complex system of familial, societal and cultural influences. However, the microsystemic framework in which child maltreatment occurs has not been sufficiently accounted for in previous measures of trauma history. In order to include this relational context, a novel survey method, the Childhood Attach...

Objectives The current study was designed to replicate and extend previous findings that demonstrate the efficacy of virtual reality (VR) technology to facilitate salient experiences of positive affect and wellbeing in response to meditative tasks, by (1) evaluating the phenomenological variables vividness, egocentricity, and immersiveness, as medi...

This letter provides an update on the activities of "The Global Collaboration on Traumatic Stress" (GC-TS) as first described by Schnyder et al. in 2017. It presents in further detail the projects of the first theme, in particular the development of and initial data on the Global Psychotrauma Screen (GPS), a brief instrument designed to screen for...

Background: The impact of traumatic experiences or adverse life experiences has been shown to potentially affect a wide range of mental health outcomes. However, there was no brief instrument to screen for a range of psychological problems in different domains after a potentially traumatic event, and for risk factors and protective factors. Objecti...

Peripersonal space (PPS) is defined as the space surrounding the body where we can reach or be reached by external entities, including objects or other individuals. PPS is an essential component of bodily self-consciousness that allows us to perform actions in the world (e.g., grasping and manipulating objects) and protect our body while interactin...

These authors contributed equally to this work. All other authors are listed in reverse alphabetical order. Neurofeedback has begun to attract the attention and scrutiny of the scientific and medical mainstream. Here, neurofeedback researchers present a consensus-derived checklist that aims to improve the reporting and experimental design standards...

Objective: We investigate the potential therapeutic application of virtual reality (VR) technology as an aid to meditation practice among persons varying in posttraumatic stress disorder (PTSD) symptoms. Method: In this within-group mixed-methods study, 96 young adults practiced both VR- and non-VR-guided meditations and reported on their experien...

Across three studies, we provide a proof-of-concept evaluation of an integrative psychotherapeutic application of virtual reality (VR) technology. Study 1 (n = 36) evaluated an unguided “safe-place” imagery task, where participants were instructed “to create a safe space… [such as] a scene, item, design, or any visual representation that makes you...

This paper emerged from a five-part exchange on trauma-related dissociation in forensic contexts between the authors and Merckelbach and colleagues (2017–2019). We find important areas of consensus, including that trauma exposure is associated with depersonalization and, occasionally, memory errors; reports of dissociative symptoms may be elevated...

Background Symptoms of anhedonia are often central to posttraumatic stress disorder (PTSD), but it is unclear how anhedonia is affected by processes induced by reliving past traumatic memories. Methods Sixty-nine male refugees (PTSD = 38) were interviewed and scanned with functional magnetic resonance imaging while viewing positive, neutral and Sc...

Intrinsic connectivity networks (ICNs), including the default mode network (DMN), central executive network (CEN), and salience network (SN) have been shown to be aberrant in patients with posttraumatic stress disorder (PTSD). The purpose of the current study was to a) compare ICN functional connectivity between PTSD, dissociative subtype PTSD (PTS...

Neurofeedback has begun to attract the attention and scrutiny of the scientific and medical mainstream. Here, neurofeedback researchers present a consensus-derived checklist that aims to improve the reporting and experimental design standards in the field.

In recent years, there has been a growing recognition of a dissociative subtype of posttraumatic stress disorder (D‐PTSD), characterized by experiences of depersonalization (DP) and derealization (DR), among individuals with PTSD. Little is known, however, about how experiences of DP and/or DR are associated with the experience of other PTSD sympto...

Network analysis has emerged as a promising new statistical methodology for traumatic stress studies. The present special issue of the Journal of Traumatic Stress amalgamates the reports of 10 studies that employed network analysis to further the field's understanding of traumatic stress. The current issue includes reports of network analyses that...

We review neuroimaging research investigating self-referential processing (SRP), that is, how we respond to stimuli that reference ourselves, prefaced by a lexical-thematic analysis of words indicative of “self-feelings”. We consider SRP as occurring verbally (V-SRP) and non-verbally (NV-SRP), both in the controlled, “top-down” form of introspectiv...

Objective: The default-mode network (DMN) and salience network (SN) have been shown to display altered connectivity in posttraumatic stress disorder (PTSD). Restoring aberrant connectivity within these networks with electroencephalogram neurofeedback (EEG-NFB) has been shown previously to be associated with acute decreases in symptoms. Here, we co...

Objectives The present study evaluated focused attention, affective response, and other subjective experiences during a mindfulness meditation exercise, relative to participant exposure to lifetime trauma, life stress experienced in the past year, and trauma-related symptoms experienced over the past month. Methods Participants were recruited from...

Background: The innate alarm system consists of a subcortical network of interconnected midbrain, lower brainstem, and thalamic nuclei, which together mediate the detection of evolutionarily-relevant stimuli. The periaqueductal gray is a midbrain structure innervated by the innate alarm system that coordinates the expression of defensive states fo...

Individuals with post-traumatic stress disorder (PTSD) typically experience states of reliving and hypervigilance; however, the dissociative subtype of PTSD (PTSD+DS) presents with additional symptoms of depersonalization and derealization. Although the insula is critical to emotion processing, its association with these contrasting symptom profile...

Post‐traumatic stress disorder (PTSD), a diagnosis that may follow the experience of trauma, has multiple symptomatic phenotypes. Generally, individuals with PTSD display symptoms of hyperarousal and of hyperemotionality in the presence of fearful stimuli. A subset of individuals with PTSD; however, elicit dissociative symptomatology (i.e., deperso...

This retrospective survey study compared the differential risk of lifetime traumatic stressors, so-called “non-traumatic stressors” experienced over the past year, referring to life events that do not meet the criteria for A1 traumatic events, and adverse childhood experiences (ACE) on severity of DSM-5 versus ICD-11 PTSD, Complex PTSD (CPTSD), and...

Background: Oculomotor movements have been shown to aid in the retrieval of episodic memories, serving as sensory cues that engage frontoparietal brain regions to reconstruct visuospatial details of a memory. Frontoparietal brain regions not only are involved in oculomotion, but also mediate, in part, the retrieval of autobiographical episodic memo...

Background: The innate alarm system, a network of interconnected midbrain, other brainstem, and thalamic structures, serves to rapidly detect stimuli in the environment prior to the onset of conscious awareness. This system is sensitive to threatening stimuli and has evolved to process these stimuli subliminally for hastened responding. Despite th...

Background: Peri-traumatic tonic immobility has been associated with the development and course of post-traumatic stress disorder. Despite serving as an adaptive late-stage defense response, tonic immobility that continues in response to post-traumatic reminders may lead to reduced functioning and a diminished sense of well-being. At present, no v...

This checklist is intended to encourage robust experimental design and clear reporting for clinical and cognitive-behavioural neurofeedback experiments.

This checklist is intended to encourage robust experimental design and clear reporting for clinical and cognitive-behavioural neurofeedback experiments. Available at https://psyarxiv.com/nyx84

Dissociation is commonly a response to trauma that can be associated with significant impairment. In order to deal with dissociation in court from a comprehensive, scientifically informed, and valid perspective, Brand, Schielke, and Brams (Psychological Injury and Law, 10, 283-297, 2017a, b) provided a balanced view of dissociation, its characteris...

Background: The four-dimensional (‘4-D’) model has been proposed as a theoretical framework to understand and delineate trauma-related dissociative experiences, categorizing symptoms into trauma-related altered states of consciousness (TRASC) and normal waking consciousness (NWC), which occur along four dimensions: time, thought, body and emotion....

Dissociative experiences have been associated with increased disease severity, chronicity, and, in some cases, reduced treatment response across trauma-related and other psychiatric disorders. A better understanding of the neurobiological mechanisms through which dissociative experiences occur may assist in identifying novel pharmacological and non...

Background The field of psychiatry would benefit significantly from developing objective biomarkers that could facilitate the early identification of heterogeneous subtypes of illness. Critically, although machine learning pattern recognition methods have been applied recently to predict many psychiatric disorders, these techniques have not been ut...

Key evidence points toward alterations in the neurocircuitry of large‐scale networks among patients with posttraumatic stress disorder (PTSD). The pulvinar is a thalamic region displaying reciprocal connectivity with the cortex and has been shown to modulate alpha synchrony to facilitate network communication. During rest, the pulvinar displays fun...

Posttraumatic stress disorder (PTSD) has been associated with a disturbance in neural intrinsic connectivity networks (ICN), including the central executive network (CEN), default mode network (DMN), and salience network (SN). Here, we conducted a preliminary investigation examining potential changes in ICN recruitment as a function of real‐time fM...

Evidence points towards alterations in the neurocircuitry of large-scale intrinsic connectivity networks among patients with posttraumatic stress disorder (PTSD) 1,9. Indeed, alterations in connectivity within and between anticorrelated networks may underlie pathophysiological differences between PTSD and the dissociative subtype (+ DS) of the diso...

Traumatic experiences have been linked to the development of altered states of consciousness affecting bodily perception, including alterations in body ownership and sense of agency, the conscious experience of the body as one’s own and under voluntary control. Severe psychological trauma and prolonged distress may lead to posttraumatic stress diso...

Trauma is a global issue. The great majority of the global burden of disease arising from mental health conditions occurs in low- and middle-income countries (LMICs), among populations in political, economic, and/or cultural transition and those struck by forced migration. These mental health problems frequently arise as a result of traumatic event...

In November 2016 researchers, clinicians, and student experts gathered in Dallas, Texas, USA for the annual meeting of the International Society for Traumatic Stress Studies (ISTSS). From the description of the meeting theme forward it was acknowledged that interdisciplinary approaches will be required to fully understand traumatic stress as a publ...

Background: The Childhood Attachment and Relational Trauma Screen (CARTS) is a computer-administered survey designed to assess retrospectively the socio-ecological context in which instances of child abuse may have occurred. To date, studies supporting the validity of the CARTS have only been undertaken in English-speaking North American population...

Objective: Intrusive negative affect and concurrent deficits in positive affect are hallmarks of posttraumatic stress disorder (PTSD). We sought to further extend the extant literature by exploring the experience of negative affect intrusion upon potentially positive situations (here termed, "negative affect interference," NAI). Method: Two stud...

Despite findings linking low trait mindfulness to higher distress, neuroticism, and psychopathology, and a large literature broadly supporting the efficacy of mindfulness meditation (MM)-related interventions in mental healthcare, surprisingly, little is yet known about what persons with psychological disorders actually experience when they practic...

Background: Posttraumatic stress disorder (PTSD) is characterized by dysregulated arousal and altered cardiac autonomic response as evidenced by decreased high-frequency heart rate variability (HF-HRV), an indirect measure of parasympathetic modulation of the heart. Indeed, subtle threatening cues can cause autonomic dysregulation, even without ex...

Mindfulness meditation (MM) and EEG-alpha neurofeedback (NFB) have both been shown to improve attentional performance and increase full 8–12-Hz EEG alpha amplitude, but no studies have compared MM and NFB on their effects for modulating EEG alpha or attentional control. Sixty-one university students were randomized to a 15-min single-session MM (n...

Background: Changes to the diagnostic criteria for PTSD in DSM-5 reflect an increased emphasis on negative cognition referring to self and other, including self-blame, and related pervasive negative affective states including for self-conscious emotions such as guilt and shame. Objective: Investigate the neural correlates of valenced self-referenti...

Background: In lieu of consciously appraising the threat via cortical sensory processing, a subcortical ‘innate alarm system’ originating in the superior colliculus (SC) may activate innate defensive responses when threat is imminent. Individuals with posttraumatic stress disorder (PTSD) demonstrate supra- and subliminal threat detection, together...

Background: Large scale neural networks, such as the default mode network (DMN), salience network (SN), and central executive (CE) network, have been shown to be altered in patients with posttraumatic stress disorder (PTSD), where electroencephalography neurofeedback has been shown to plastically modulate these networks. Using real-time fMRI neurof...