Characteristics of memories for near-death experiences

The distorted memories of patients treated in the intensive care unit during the COVID-19 pandemic: A qualitative study

BACKGROUND

During the COVID-19 pandemic, patients cared for in the intensive care unit were exposed to many risk factors for developing delirium and subsequent distorted memories. Further, seeing healthcare professionals who have been dressed in personal protective equipment and face masks could have affected the patients' memories. Therefore, the aim of this study was to explore memories and how they are experienced and managed by former patients who have been treated for COVID-19 in an intensive care unit.

METHODS

Sixteen former patients treated for COVID-19 at a large emergency hospital in Sweden were interviewed 3-8 months after discharge from the intensive care unit. The data were interpreted using thematic analysis. The Consolidated Criteria for Reporting Qualitative Research checklist was followed in the reporting of the study.

FINDINGS

Participants' descriptions of their memories of treatment in the intensive care unit for COVID-19 generated three themes: 'Distorted truth' the content in the memories which implied facing death in an unreal distorted environment. 'Captive,' was the experience and feelings linked to memories with a feeling of being exposed and alone, and 'Coping with memories' explained how participants managed the implications of the memories using a mixture of strategies.

CONCLUSIONS

For former patients who were admitted to an intensive care unit after a diagnosis of COVID-19, memories caused considerable distress, which were similar to other intensive care patientś experiences, before the pandemic. Emotion-focused and problem-focused strategies could be used to cope with these memories. Healthcare professionals wearing protective equipment gave the patient a distant feeling, but more important was to be treated with attention/care and respect.

IMPLICATIONS FOR CLINICAL PRACTICE

Awareness of the impact of distorted memories on patients who are severely ill and their needs and strategies to cope with these memories can form the basis for early interventions that promotes well-being during care and recovery. Healthcare professionals have an important task to inform patients and their family members about the existence of distorted memories, and talk about the patients' experience of them, to facilitate their recovery.

A Study of Near-Death Experience in Patients With Chronic Kidney Disease

BACKGROUND

The near-death experiences (NDE) in dialysis patients of our country have not been previously studied. The objective of this study is to investigate the characteristics of NDEs in patients on dialysis.

MATERIALS AND METHODS

We performed a cross sectional study of the adult patients of chronic kidney disease stage 5 without dialysis and on dialysis who survived cardiac arrest by cardiopulmonary resuscitation (CPR) as per ACLS (Advanced Cardiac Life Support) guidelines and who sustained pulseless ventricular tachycardia/ventricular fibrillation and received CPR and/or direct cardioversion. We used two scales, Greyson's NDE scale and Ring's Weighted Core Experience Index (WCEI).

RESULTS

We performed the study between 2016 and 2018. A total of 29 patients were included. The data based on Greyson's NDE scale and Ring's Weighted Core Experience Index (WCEI)were collected.

CONCLUSIONS

Our study brings a perspective of NDE in CKD and dialysis patients. A similar study of NDE in dialysis patients should be considered by other nephrologists.

The Near-Death Experience Content (NDE-C) scale: Development and psychometric validation

As interest grows in near-death experiences (NDEs), it is increasingly important to accurately identify them to facilitate empirical research and reproducibility among assessors. We aimed (1) to reassess the psychometric properties of the NDE scale developed by Greyson (1983) and (2) to validate the Near-Death Experience Content (NDE-C) scale that quantifies NDEs in a more complete way. Internal consistency, construct and concurrent validity analyses were performed on the NDE scale. Based on those results and the most recent empirical evidence, we then developed a new 20-item scale. Internal consistency, explanatory and confirmatory factor, concurrent and discriminant validity analyses were conducted. Results revealed (1) a series of weaknesses in the NDE scale, (2) a 5-factor structure covering relevant dimensions and the very good psychometric properties of the NDE-C scale, including very good internal consistency (Cronbach α = 0.85) and concurrent validity (correlations above 0.76). This new reliable scale should facilitate future research.

Remembering the Super-Typhoon: Some, but Not All, Qualities of First-Hand Survivor Memories of Natural Disaster Are Similar to Near Death Experience and Flashbulb Memory Accounts

The strongest storm in Philippines history, super-typhoon Haiyan, barreled through central Philippines in 2013 and left a high death toll and extensive destruction in its wake. Past studies have investigated Fading Affect Bias (FAB) in extremely negative situations like the death of a loved one and found that the FAB generally occurs in those extreme situations, but this study is the first to assess FAB in first-hand memories for a natural disaster survival situation. The FAB phenomenon is the tendency for emotional intensity associated with negative memories for events to fade over time and emotional intensity for positive events stays relatively stable over time. Researchers collected memories for the super-typhoon from survivors three years after the event. Results showed that negative emotional intensity for the event faded after the event. Emotion in comparison positive memories for non-typhoon events did not fade, and emotion in comparison negative memories faded, following results in several other FAB studies. The Positive and Negative Affect Scale (PANAS) was used as an initial assessment of mood before the study began, and PANAS scores reliably predicted current emotional intensity scores. Memory vividness and emotional intensity in first-hand accounts of a natural disaster experience behave like vividness and intensity in flashbulb memories, but details in first-hand accounts are similar to the amount of details in memories of near-death experiences. How memory rehearsal behaves in relation to time elapsed since event has yet to be captured for first-hand survival experiences.

Near-Death Experience Memories Include More Episodic Components Than Flashbulb Memories

Memories of near-death experiences (NDEs) are recalled as "realer" than memories of other real or imagined events. Given their rich phenomenology, emotionality and consequentiality, it was hypothesized that they could meet some aspects of the definition of flashbulb memories. We aimed to identify and compare the episodic and non-episodic information provided in verbal recollections of NDE, flashbulb, and control autobiographical memories. The phenomenological characteristics and centrality of the memories were also compared. Twenty-five participants who had lived a NDE in a life-threatening situation were interviewed and completed the Memory Characteristics Questionnaires as well as the Centrality of Event Scale for their NDE, a flashbulb and another autobiographical memory used as control. Overall, transcribed NDE verbal recollections included a higher overall amount of details and more internal/episodic information than control autobiographical and flashbulb memories. Moreover, flashbulb memories were associated to a lower intensity of feelings while remembering and a lower personal importance, and are less reactivated and less susceptible to be remembered from a first person perspective compared to NDE and control autobiographical memories. Finally, NDE memories are the most central memories to experiencers' identity, followed by control autobiographical and then by flashbulb memories. These findings corroborate previous studies highlighting the impact and uniqueness of NDE memories.

Near-Death Experience as a Probe to Explore (Disconnected) Consciousness

Forty-five years ago, the first evidence of near-death experience (NDE) during comatose state was provided, setting the stage for a new paradigm for studying the neural basis of consciousness in unresponsive states. At present, the state of consciousness associated with NDEs remains an open question. In the common view, consciousness is said to disappear in a coma with the brain shutting down, but this is an oversimplification. We argue that a novel framework distinguishing awareness, wakefulness, and connectedness is needed to comprehend the phenomenon. Classical NDEs correspond to internal awareness experienced in unresponsive conditions, thereby corresponding to an episode of disconnected consciousness. Our proposal suggests new directions for NDE research, and more broadly, consciousness science.

Neurophenomenology of near-death experience memory in hypnotic recall: a within-subject EEG study

The neurobiological basis of near-death experiences (NDEs) is unknown, but a few studies attempted to investigate it by reproducing in laboratory settings phenomenological experiences that seem to closely resemble NDEs. So far, no study has induced NDE-like features via hypnotic modulation while simultaneously measuring changes in brain activity using high-density EEG. Five volunteers who previously had experienced a pleasant NDE were invited to re-experience the NDE memory and another pleasant autobiographical memory (dating to the same time period), in normal consciousness and with hypnosis. We compared the hypnosis-induced subjective experience with the one of the genuine experience memory. Continuous high-density EEG was recorded throughout. At a phenomenological level, we succeeded in recreating NDE-like features without any adverse effects. Absorption and dissociation levels were reported as higher during all hypnosis conditions as compared to normal consciousness conditions, suggesting that our hypnosis-based protocol increased the felt subjective experience in the recall of both memories. The recall of a NDE phenomenology was related to an increase of alpha activity in frontal and posterior regions. This study provides a proof-of-concept methodology for studying the phenomenon, enabling to prospectively explore the NDE-like features and associated EEG changes in controlled settings.

Semiology and Mechanisms of Near-Death Experiences

PURPOSE OF REVIEW

Near-death experiences (NDEs) are conscious perceptual experiences, including self-related emotional, spiritual, and mystical experiences, occurring in close encounters with death or in non-life-threatening situations. The origin of NDEs remains unknown. Here, we review recent advances in the understanding of NDE semiology and pathophysiology.

RECENT FINDINGS

Recent prospective studies confirm that NDEs reflect a spectrum of highly distinctive memories which are associated with negative or positive emotions and can be influenced by the nature of the causal event, but the temporal sequence with which these images unfold is variable. Some drugs, notably ketamine, may lead to experiences that are similar or even identical to NDEs. New models extend previous neural network theories and include aspects of evolutionary and quantum theories. Although the factual existence of NDEs is no longer doubted and the semiology well-described, a pathophysiological model that includes all aspects of NDEs is still lacking.

A systematic analysis of distressing near-death experience accounts

Near-death experiences (NDEs) are usually associated with positive affect, however, a small proportion are considered distressing. We aimed to look into the proportion of distressing NDEs in a sample of NDE narratives, categorise distressing narratives according to Greyson and Bush's classification (inverse, void or hellish), and compare distressing and "classical" NDEs. Participants wrote down their experience, completed the Memory Characteristics Questionnaire (assessing the phenomenology of memories) and the Greyson scale (characterising content of NDEs). The proportion of suicidal attempts, content and intensity of distressing and classical NDEs were compared using frequentist and Bayesian statistics. Distressing NDEs represent 14% of our sample (n = 123). We identified 8 inverse, 8 hellish and 1 void accounts. The proportion of suicide survivors is higher in distressing NDEs as compared to classical ones. Finally, memories of distressing NDEs appear as phenomenologically detailed as classical ones. Distressing NDEs deserve careful consideration to ensure their integration into experiencers' identity.

Memories of near-death experiences: are they self-defining?

Some people report memories of near-death experiences (NDEs) after facing situations of impending death and these memories appear to have significant consequences on their lives (here referred to as “real NDE experiencers”; real NDErs). We assessed to what extent NDE memories are considered self-defining: memories that help people to define clearly how they see themselves. We screened 71 participants using the Greyson NDE scale (48 real NDErs and 23 NDErs-like who had lived a similar experience in absence of a threat to their life). Participants described their two main self-defining memories (SDMs). For each SDM, they completed the Centrality of Event Scale (CES) to assess how central the event is to their identity. The two subgroups did not differ regarding the proportion of NDErs who recalled their NDE (30 real NDErs out of 48 and 11 NDErs-like out of 23). Real NDErs and NDErs-like who recalled their NDE (n = 41) reported richer experiences as assessed by the Greyson NDE scale. Furthermore, these participants rated their NDE memory as more central to their identity as compared to other SDMs, and the richness of the NDE memory was positively associated to its centrality (CES scores). Overall, these findings suggest that the self-defining aspect of the experience might be related to its phenomenological content rather than its circumstances of occurrence. The self-defining status of NDE memories confirms that they constitute an important part of NDErs’ personal identity and highlights the importance for clinicians to facilitate their integration within the self.

Neurochemical models of near-death experiences: A large-scale study based on the semantic similarity of written reports

The real or perceived proximity to death often results in a non-ordinary state of consciousness characterized by phenomenological features such as the perception of leaving the body boundaries, feelings of peace, bliss and timelessness, life review, the sensation of traveling through a tunnel and an irreversible threshold. Near-death experiences (NDEs) are comparable among individuals of different cultures, suggesting an underlying neurobiological mechanism. Anecdotal accounts of the similarity between NDEs and certain drug-induced altered states of consciousness prompted us to perform a large-scale comparative analysis of these experiences. After assessing the semantic similarity between ≈15,000 reports linked to the use of 165 psychoactive substances and 625 NDE narratives, we determined that the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine consistently resulted in reports most similar to those associated with NDEs. Ketamine was followed by Salvia divinorum (a plant containing a potent and selective κ receptor agonist) and a series of serotonergic psychedelics, including the endogenous serotonin 2A receptor agonist N,N-Dimethyltryptamine (DMT). This similarity was driven by semantic concepts related to consciousness of the self and the environment, but also by those associated with the therapeutic, ceremonial and religious aspects of drug use. Our analysis sheds light on the long-standing link between certain drugs and the experience of "dying", suggests that ketamine could be used as a safe and reversible experimental model for NDE phenomenology, and supports the speculation that endogenous NMDA antagonists with neuroprotective properties may be released in the proximity of death.

Full Neurological Recovery From Escherichia coli Meningitis Associated With Near-Death Experience

A 54-year-old otherwise healthy man presented with altered mental status. On admission, the patient was confused and agitated, with a Glasgow Coma Scale (GCS) score of 11, suggesting moderate brain injury. He was sedated, placed on a ventilator, and started on tobramycin and ceftazidime for presumed bacterial meningitis, but switched to ceftriaxone once cultures returned as Escherichia coli. During his 8-day hospitalization, his mental status fluctuated from confused to nonresponsive, with GCS scores between 6 and 11. Although E. coli meningitis has a high rate of neurological complications and death, this patient recovered completely without any deficits, and recalled an elaborate near-death experience that occurred during his coma. This case highlights the importance of studying near-death experiences occurring during compromised brain function to further our understanding of the brain and consciousness.

Qualitative thematic analysis of the phenomenology of near-death experiences

Near-death experiences (NDEs) refer to profound psychological events that can have an important impact on the experiencers’ (NDErs) lives. Previous studies have shown that NDEs memories are phenomenologically rich. In the present study, we therefore aimed to extract the common themes (referred to as “features” in the NDE literature) reported by NDErs by analyzing all the concepts stored in the narratives of their experiences. A qualitative thematic analysis has been carried out on 34 cardiac arrest survivors’ NDE narratives. Our results shed the light on the structure of the narratives by identifying 10 “time-bounded” themes which refer to isolated events encountered during the NDE and 1 “transversal” theme which characterizes the whole narrative and generally appears as a retrospective comment of self-reflection on the experience. The division of narratives into themes provides us with detailed information about the vocabulary used by NDErs to describe their experience. This established thematic method enables a rigorous description of the phenomenon, ensuring the inclusion of all self-reported manifestations of themes in narratives.