Dying to know the truth: visions of a dying brain, or false memories?

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.

Electrocerebral Signature of Cardiac Death

BACKGROUND

Electroencephalography (EEG) findings following cardiovascular collapse in death are uncertain. We aimed to characterize EEG changes immediately preceding and following cardiac death.

METHODS

We retrospectively analyzed EEGs of patients who died from cardiac arrest while undergoing standard EEG monitoring in an intensive care unit. Patients with brain death preceding cardiac death were excluded. Three events during fatal cardiovascular failure were investigated: (1) last recorded QRS complex on electrocardiogram (QRS₀), (2) cessation of cerebral blood flow (CBF₀) estimated as the time that blood pressure and heart rate dropped below set thresholds, and (3) electrocerebral silence on EEG (EEG₀). We evaluated EEG spectral power, coherence, and permutation entropy at these time points.

RESULTS

Among 19 patients who died while undergoing EEG monitoring, seven (37%) had a comfort-measures-only status and 18 (95%) had a do-not-resuscitate status in place at the time of death. EEG₀ occurred at the time of QRS₀ in five patients and after QRS₀ in two patients (cohort median - 2.0, interquartile range - 8.0 to 0.0), whereas EEG₀ was seen at the time of CBF₀ in six patients and following CBF₀ in 11 patients (cohort median 2.0 min, interquartile range - 1.5 to 6.0). After CBF₀, full-spectrum log power (p < 0.001) and coherence (p < 0.001) decreased on EEG, whereas delta (p = 0.007) and theta (p < 0.001) permutation entropy increased.

CONCLUSIONS

Rarely may patients have transient electrocerebral activity following the last recorded QRS (less than 5 min) and estimated cessation of cerebral blood flow. These results may have implications for discussions around cardiopulmonary resuscitation and organ donation.

Compressed Life Review: Extreme Manifestation of Autobiographical Memory in Eye-Tracker

The compressed life review (CLR) is a mnemonic illusion of having "your entire life flashing before your eyes". This research was guided by concerns over the retrospective methodology used in CLR studies. To depart from this methodology, I considered the long-term working memory (WM), "concentric", and "activation-based" models of memory. A novel theoretically rooted laboratory-based experimental technique aimed to elicit the CLR-like experience with no risk to healthy participants was developed. It consists of listening to superimposed audio recordings of previously trained verbal cues to an individually composed set of self-defining memories (SDMs). The technique evoked a self-reported CLR-like experience in 10 out of 20 participants. A significant similarity in eye movement patterns between a single SDM condition and a choir of SDM conditions in self-reported CLR experiencers was confirmed. In both conditions, stimuli caused relative visual immobilization, in contrast to listening to a single neutral phrase, and a choir of neutral phrases that led to active visual exploration. The data suggest that CLR-like phenomenology may be successfully induced by triggering short-term access to the verbally cued SDMs and may be associated with specific patterns of visual activity that are not reportedly involved with deliberate autobiographical retrieval.

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.

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.

Near-Death Experiences in patients with locked-in syndrome: Not always a blissful journey

Memories of Near-Death Experiences (NDEs) most often are recounted as emotionally positive events. At present, no satisfactory explanatory model exists to fully account for the rich phenomenology of NDEs following a severe acute brain injury. The particular population of patients with locked-in syndrome (LIS) provides a unique opportunity to study NDEs following infratentorial brain lesions. We here retrospectively characterized the content of NDEs in 8 patients with LIS caused by an acute brainstem lesion (i.e., "LIS NDEs") and 23 NDE experiencers after coma with supratentorial lesions (i.e., "classical NDEs"). Compared to "classical NDEs", "LIS NDEs" less frequently experienced a feeling of peacefulness or well-being. It could be hypothesized that NDEs containing less positive emotions might have a specific neuroanatomical substrate related to impaired pontine/paralimbic connectivity or alternatively might be related to the emotional distress caused by the presence of conscious awareness in a paralyzed body.

Near-death experiences in non-life-threatening events and coma of different etiologies

Background: Near death experiences (NDEs) are increasingly being reported as a clearly identifiable physiological and psychological reality of clinical significance. However, the definition and causes of the phenomenon as well as the identification of NDE experiencers is still a matter of debate. To date, the most widely used standardized tool to identify and characterize NDEs in research is the Greyson NDE scale. Using this scale, retrospective and prospective studies have been trying to estimate their incidence in various populations but few studies have attempted to associate the experiences' intensity and content to etiology.

Methods: This retrospective investigation assessed the intensity and the most frequently recounted features of self-reported NDEs after a non-life-threatening event (i.e., “NDE-like” experience) or after a pathological coma (i.e., “real NDE”) and according to the etiology of the acute brain insult. We also compared our retrospectively acquired data in anoxic coma with historical data from the published literature on prospective post-anoxic studies using the Greyson NDE scale.

Results: From our 190 reports who met the criteria for NDE (i.e., Greyson NDE scale total score >7/32), intensity (i.e., Greyson NDE scale total score) and content (i.e., Greyson NDE scale features) did not differ between “NDE-like” (n = 50) and “real NDE” (n = 140) groups, nor within the “real NDE” group depending on the cause of coma (anoxic/traumatic/other). The most frequently reported feature was peacefulness (89–93%). Only 2 patients (1%) recounted a negative experience. The overall NDE core features' frequencies were higher in our retrospective anoxic cohort when compared to historical published prospective data.

Conclusions: It appears that “real NDEs” after coma of different etiologies are similar to “NDE-like” experiences occurring after non-life threatening events. Subjects reporting NDEs retrospectively tend to have experienced a different content compared to the prospective experiencers.

Near death experiences: a multidisciplinary hypothesis

Recently, we proposed a novel biophysical concept regarding on the appearance of brilliant lights during near death experiences (NDEs) (Bókkon and Salari, 2012). Specifically, perceiving brilliant light in NDEs has been proposed to arise due to the reperfusion that produces unregulated overproduction of free radicals and energetically excited molecules that can generate a transient enhancement of bioluminescent biophotons in different areas of the brain, including retinotopic visual areas. If this excess of bioluminescent photon emission exceeds a threshold in retinotopic visual areas, this can appear as (phosphene) lights because the brain interprets these intrinsic retinotopic bioluminescent photons as if they originated from the external physical world. Here, we review relevant literature that reported experimental studies (Imaizumi et al., 1984; Suzuki et al., 1985) that essentially support our previously published conception, i.e., that seeing lights in NDEs may be due to the transient enhancement of bioluminescent biophotons. Next, we briefly describe our biophysical visual representation model that may explain brilliant lights experienced during NDEs (by phosphenes as biophotons) and REM sleep associated dream-like intrinsic visual imageries through biophotons in NDEs. Finally, we link our biophysical visual representation notion to self-consciousness that may involve extremely low-energy quantum entanglements. This article is intended to introduce novel concepts for discussion and does not pretend to give the ultimate explanation for the currently unanswerable questions about matter, life and soul; their creation and their interrelationship.

Infrequent near death experiences in severe brain injury survivors - A quantitative and qualitative study

Background:

Near death experiences (NDE) are receiving increasing attention by the scientific community because not only do they provide a glimpse of the complexity of the mind-brain interactions in ‘near-death’ circumstances but also because they have significant and long lasting effects on various psychological aspects of the survivors. The over-all incidence-reports of NDEs in literature have varied widely from a modest Figure of 10% to around 35%, even up to an incredible Figure of 72% in persons who have faced close brush with death. Somewhat similar to this range of difference in incidences are the differences prevalent in the opinions that theorists and researchers harbor around the world for explaining this phenomena. None the less, objective evidences have supported physiological theories the most. A wide range of physiological processes have been targeted for explaining NDEs. These include cerebral anoxia, chemical alterations like hypercapnia, presence of endorphins, ketamine, and serotonin, or abnormal activity of the temporal lobe or the limbic system. In spite of the fact that the physiological theories of NDEs have revolved around the derangements in brain, no study till date has taken up the task of evaluating the experiences of near-death in patients where specific injury has been to brain. Most of them have evaluated NDEs in cardiac-arrest patients. Post-traumatic coma is one such state regarding which the literature seriously lacks any information related to NDEs. Patients recollecting any memory of their post-traumatic coma are valuable assets for NDE researchers and needs special attention.

Materials and Methods:

Our present study was aimed at collecting this valuable information from survivors of severe head injury after a prolonged coma. The study was conducted in the head injury department of Guangdong 999 Brain hospital, Guangzhou, China. Patients included in the study were the ones Recovered from the posttraumatic coma following a severe head injury. A total of 86 patients were chosen. Near death experience scale (NDES) score of 7 or more was used as the criteria of screening NDE experiences. After identifying such individuals, the Prakash-modification of the Interpretative Phenomenological Analysis (IPA) was used to interview and record the data for qualitative analysis.

Results:

We found that contrary to earlier incidence reports, NDEs in post head injury patients were markedly low. Only 3 out of 86 of the patients recruited had a clear and confident experience of NDE. We conducted a qualitative study to explore further into these experiences. IPA of these 3 patients revealed four master themes: 1. Unique light visions 2. Intense feelings of astonishment, pleasure, and fear 3. The sense of helplessness 4. Supernatural but rationality of experience.

Conclusion:

NDE is uncommon in head-injury cases as compared to other near-death conditions. But the persons experiencing it have immense impacts on their belief systems and emotions. This experience should be further explored by studies of larger samples.

Characteristics of near-death experiences memories as compared to real and imagined events memories

Since the dawn of time, Near-Death Experiences (NDEs) have intrigued and, nowadays, are still not fully explained. Since reports of NDEs are proposed to be imagined events, and since memories of imagined events have, on average, fewer phenomenological characteristics than real events memories, we here compared phenomenological characteristics of NDEs reports with memories of imagined and real events. We included three groups of coma survivors (8 patients with NDE as defined by the Greyson NDE scale, 6 patients without NDE but with memories of their coma, 7 patients without memories of their coma) and a group of 18 age-matched healthy volunteers. Five types of memories were assessed using Memory Characteristics Questionnaire (MCQ – Johnson et al., 1988): target memories (NDE for NDE memory group, coma memory for coma memory group, and first childhood memory for no memory and control groups), old and recent real event memories and old and recent imagined event memories. Since NDEs are known to have high emotional content, participants were requested to choose the most emotionally salient memories for both real and imagined recent and old event memories. Results showed that, in NDE memories group, NDE memories have more characteristics than memories of imagined and real events (p<0.02). NDE memories contain more self-referential and emotional information and have better clarity than memories of coma (all ps<0.02). The present study showed that NDE memories contained more characteristics than real event memories and coma memories. Thus, this suggests that they cannot be considered as imagined event memories. On the contrary, their physiological origins could lead them to be really perceived although not lived in the reality. Further work is needed to better understand this phenomenon.

Near-Death-Like Experiences without Life-Threatening Conditions or Brain Disorders: A Hypothesis from a Case Report

Near-death experiences (NDEs) are profound psychic experiences commonly occurring in life-threatening conditions. They include feeling a sense of peace, of seeing a bright light, encountering deceased relatives or religious figures, and of transcending space and time. To explain them, it has been suggested that they stem from brain disorders and/or psychological reactions to approaching death, a sort of wishful thinking in response to the perceived threat. This is a report on a case with most of the features typical of NDEs except that it occurred entirely without any life-threatening conditions. This evidence is theoretically incompatible with either of the above hypotheses, suggesting that a broader interpretation of the phenomenon is needed.

Near-death experiences between science and prejudice

Science exists to refute dogmas; nevertheless, dogmas may be introduced when undemonstrated scientific axioms lead us to reject facts incompatible with them. Several studies have proposed psychobiological interpretations of near-death experiences (NDEs), claiming that NDEs are a mere byproduct of brain functions gone awry; however, relevant facts incompatible with the ruling physicalist and reductionist stance have been often neglected. The awkward transcendent look of NDEs has deep epistemological implications, which call for: (a) keeping a rigorously neutral position, neither accepting nor refusing anything a priori; and (b) distinguishing facts from speculations and fallacies. Most available psychobiological interpretations remain so far speculations to be demonstrated, while brain disorders and/or drug administration in critical patients yield a well-known delirium in intensive care and anesthesia, the phenomenology of which is different from NDEs. Facts can be only true or false, never paranormal. In this sense, they cannot be refused a priori even when they appear implausible with respect to our current knowledge: any other stance implies the risk of turning knowledge into dogma and the adopted paradigm into a sort of theology.

Near-Death Experience: Out-of-Body and Out-of-Brain?

During the last decades, several clinical cases have been reported where patients described profound subjective experiences when near-death, a phenomenon called “near-death experience” (NDE). Recurring features in the accounts involving bright lights and tunnels have sometimes been interpreted as evidence of a new life after death; however the origin of such experiences is largely unknown, and both biological and psychological interpretations have been suggested. The study of NDEs represents one of the most important topics of cognitive neuroscience. In the present paper the current state of knowledge has been reviewed, with particular regard to the main features of NDE, scientific explanations and the theoretical debate surrounding this phenomenon.

Consistency of near-death experience accounts over two decades: Are reports embellished over time?

AIM

"Near-death experiences," commonly reported after clinical death and resuscitation, may require intervention and, if reliable, may elucidate altered brain functioning under extreme stress. It has been speculated that accounts of near-death experiences are exaggerated over the years. The objective of this study was to test the reliability over two decades of accounts of near-death experiences.

METHODS

Seventy-two patients with near-death experience who had completed the NDE scale in the 1980s (63% of the original cohort still alive) completed the scale a second time, without reference to the original scale administration. The primary outcome was differences in NDE scale scores on the two administrations. The secondary outcome was the statistical association between differences in scores and years elapsed between the two administrations.

RESULTS

Mean scores did not change significantly on the total NDE scale, its 4 factors, or its 16 items. Correlation coefficients between scores on the two administrations were significant at P<0.001 for the total NDE scale, for its 4 factors, and for its 16 items. Correlation coefficients between score changes and time elapsed between the two administrations were not significant for the total NDE scale, for its 4 factors, or for its 16 items.

CONCLUSION

Contrary to expectation, accounts of near-death experiences, and particularly reports of their positive affect, were not embellished over a period of almost two decades. These data support the reliability of near-death experience accounts.

Near-death experiences in cardiac arrest survivors

Near-death experiences (NDEs) have become the focus of much interest in the last 30 years or so. Such experiences can occur both when individuals are objectively near to death and also when they simply believe themselves to be. The experience typically involves a number of different components including a feeling of peace and well-being, out-of-body experiences (OBEs), entering a region of darkness, seeing a brilliant light, and entering another realm. NDEs are known to have long-lasting transformational effects upon those who experience them. An overview is presented of the various theoretical approaches that have been adopted in attempts to account for the NDE. Spiritual theories assume that consciousness can become detached from the neural substrate of the brain and that the NDE may provide a glimpse of an afterlife. Psychological theories include the proposal that the NDE is a dissociative defense mechanism that occurs in times of extreme danger or, less plausibly, that the NDE reflects memories of being born. Finally, a wide range of organic theories of the NDE has been put forward including those based upon cerebral hypoxia, anoxia, and hypercarbia; endorphins and other neurotransmitters; and abnormal activity in the temporal lobes. Finally, the results of studies of NDEs in cardiac arrest survivors are reviewed and the implications of these results for our understanding of mind-brain relationships are discussed.