Some people who have survived a life-threateningcrisis report an extraordinary experience. Near-deathexperience occurs with increasing frequency becauseof improved survival rates resulting from modern techniquesof resuscitation.
The content of NDE and the effects onpatients seem similar worldwide, across all cultures and times.The subjective nature and absence of a frame of referencefor this experience lead to individual, cultural, and religiousfactors determining the vocabulary used to describe and interpretthe experience.1
NDE are reported in many circumstances:cardiac arrest in myocardial infarction (clinical death),shock in postpartum loss of blood or in perioperative complications,septic or anaphylactic shock, electrocution, coma resultingfrom traumatic brain damage, intracerebral hemorrhage or cerebralinfarction, attempted suicide, near-drowning or asphyxia,and apnea.
Such experiences are also reported bypatients with serious but not immediately life-threateningdiseases, in those with serious depression, or without clearcause in fully conscious people. Similar experiences to near-deathones can occur during the terminal phase of illness, and arecalled deathbed visions.
Identical experiences to NDE, so-calledfear-death experiences, are mainly reported after situationsin which death seemed unavoidable: serious traffic accidents,mountaineering accidents, or isolation such as with shipwreck.
Several theories on the origin of NDEhave been proposed. Some think the experience is caused byphysiological changes in the brain, such as brain cells dyingas a result of cerebral anoxia.2-4 Other theories encompassa psychological reaction to approaching death,5 or a combinationof such reaction and anoxia.6
Such experiences could also be linkedto a changing state of consciousness (transcendence), in whichperception, cognitive functioning, emotion, and sense of identityfunction independently from normal body-linked waking consciousness.7
People who have had an NDE are psychologicallyhealthy; although some show non-pathological signs of dissociation.7Such people do not differ from controls with respect to age,sex, ethnic origin, religion, or degree of religious belief.1
Studies on NDE1,3,8,9 have been retrospectiveand very selective with respect to patients. In retrospectivestudies, 5-10 years can elapse between occurrence of the experienceand its investigation, which often prevents accurate assessmentof physiological and pharmacological factors.
In retrospective studies, about 45%1of adults and up to 85% of children10 who had a life-threateningillness were estimated to have had an NDE. A randominvestigation of more than 2000 Germans showed 43%to have had an NDE at a mean age of 22 years.11
Differences in estimates of frequencyand uncertainty as to causes of this experience result fromvarying definitions of the phenomenon, and from inadequatemethods of research.12
Patients' transformational processes afteran NDE are very similar1,3,13-16 and encompass life-changinginsight, heightened intuition, and disappearance of fear ofdeath. Assimilation and acceptance of these changes is thoughtto take at least several years.15
The authors defined NDE as the reportedmemory of all impressions during a special state of consciousness,including specific elements such as out-of-body experience,pleasant feelings, and seeing a tunnel, a light, deceasedrelatives, or a life review.
They defined clinical death as a periodof unconsciousness caused by insufficient blood supply tothe brain because of inadequate blood circulation, breathing,or both. If, in this situation, CPR is not started within5-10 min, irreparable damage is done to the brain and thepatient will die.
The results show that medical factorscannot account for occurrence of NDE; although all patientshad been clinically dead, most did not have NDE. Furthermore,seriousness of the crisis was not related to occurrence ordepth of the experience.
If purely physiological factors resultingfrom cerebral anoxia caused NDE, most of the patients shouldhave had this experience. Patients' medication was also unrelatedto frequency of NDE. Psychological factors are unlikely tobe important as fear was not associated with NDE.
Only 12% of patients had a core NDE, andthis figure might be an overestimate. True frequency of theexperience is likely to be about 10%, or 5% if based on numberof resuscitations rather than number of resuscitated patients.Patients who survive several CPRs in hospital have a significantlyhigher chance of NDE.
Good short-termmemory seems to be essential for remembering NDE.
Patients with memory defects after prolongedresuscitation reported fewer experiences than other patientsin our study.
Forgetting or repressing such experiencesin the first days after CPR was unlikely to have occurredin the remaining patients, because no relation was found betweenfrequency of NDE and date of first interview.
However, at 2-year follow-up, two patientsremembered a core NDE and two an NDE that consisted of onlypositive emotions that they had not reported shortly afterCPR, presumably because of memory defects at that time. Itis remarkable that people could recall their NDE almost exactlyafter 2 and 8 years.
Our finding that women have deeper experiencesthan men has been confirmed in two other studies,1,7 althoughin one,7 only in those cases in which women had an NDE resultingfrom disease.
Our findings show that the process ofchange after NDE tends to take several years to consolidate.Presumably, besides possible internal psychological processes,one reason for this has to do with society's negative responseto NDE, which leads individuals to deny or suppress theirexperience for fear of rejection or ridicule.
Thus, social conditioning causes NDE tobe traumatic, although in itself it is not a psychotraumaticexperience. As a result, the effects of the experience canbe delayed for years, and only gradually and with difficultyis an NDE accepted and integrated. Furthermore, the long-lastingtransformational effects of an experience that lasts for onlya few minutes of cardiac arrest is a surprising and unexpectedfinding.
Several theories have been proposed toexplain NDE.
Wedid not show that psychological, neurophysiological, or physiologicalfactors caused these experiences after cardiac arrest.
Neurophysiological processes must playsome part in NDE. Similar experiences can be induced throughelectrical stimulation of the temporal lobe (and hence ofthe hippocampus) during neurosurgery for epilepsy,23 withhigh carbon dioxide levels (hypercarbia),24 and in decreasedcerebral perfusion resulting in local cerebral hypoxia asin rapid acceleration during training of fighter pilots,25or as in hyperventilation followed by valsalva manoeuvre.4
Ketamine-induced experiences resultingfrom blockage of the NMDA receptor,26 and the role of endorphin,serotonin, and enkephalin have also been mentioned,27 as havenear-death-like experiences after the use of LSD,28 psilocarpine,and mescaline.21
These induced experiences can consistof unconsciousness, out-of-body experiences, and perceptionof light or flashes of recollection from the past.
These recollections, however, consistof fragmented and random memories unlike the panoramic life-reviewthat can occur in NDE. Further, transformational processeswith changing life-insight and disappearance of fear of deathare rarely reported after induced experiences.
Thus, induced experiences are not identicalto NDE, and so, besides age, an unknown mechanism causes NDEby stimulation of neurophysiological and neurohumoral processesat a subcellular level in the brain in only a few cases duringa critical situation such as clinical death. These processesmight also determine whether the experience reaches consciousnessand can be recollected.
With lack of evidence for any other theoriesfor NDE, the thus far assumed, but never proven, concept thatconsciousness and memories are localized in the brain shouldbe discussed.
How could a clear consciousness outsideone's body be experienced at the moment that the brain nolonger functions during a period of clinical death with flatEEG?22
Also, in cardiac arrest the EEG usuallybecomes flat in most cases within about 10 s from onset ofsyncope.29,30 Furthermore, blind people have described veridicalperception during out-of-body experiences at the time of thisexperience.31 NDE pushes at the limits of medical ideas aboutthe range of human consciousness and the mind-brain relation.
Another theory holds that NDE might bea changing state of consciousness (transcendence), in whichidentity, cognition, and emotion function independently fromthe unconscious body, but retain the possibility of non-sensoryperception.7,8,22,28,31
Lancet December15, 2001; 358: 2039-45
The Lancet is one of the world's mostrespected medical journals. So when it published an articlein its current edition in which scientists claim to have PROOFthat humans have a life after death that exists independentlyof the body that it inhabits, folks are sitting up and takingnotice.
Many readers of this newsletter havestrong spiritual convictions about the existence of the soul,but it is wonderful to have medical science support theseconvictions.