Near-death experience in survivors of cardiac arrest: a prospective study
in the
Netherlands
Pim van Lommel, Ruud van Wees, Vincent Meyers, Ingrid Elfferich
Division of Cardiology, Hospital Rijnstate, Arnhem, Netherlands (P van
Lommel
MD); Tilburg, Netherlands (R van Wees PhD); Nijmegen, Netherlands (V Meyers
PhD); and Capelle a/d Ijssel, Netherlands (I Elfferich PhD)
Correspondence to: Dr Pim van Lommel, Division of Cardiology, Hospital
Rijnstate, PO
Box 9555, 6800 TA Arnhem, Netherlands (e-mail:pimvanlommel@wanadoo.nl)
Summary
Introduction
Methods
Results
Discussion
References
Summary
Background Some people report a near-death experience (NDE) after a life-threatening
crisis. We aimed to establish the cause of this experience and assess factors
that
affected its frequency, depth, and content.
Methods In a prospective study, we included 344 consecutive cardiac patients
who
were successfully resuscitated after cardiac arrest in ten Dutch hospitals.
We compared
demographic, medical, pharmacological, and psychological data between patients
who
reported NDE and patients who did not (controls) after resuscitation. In
a longitudinal
study of life changes after NDE, we compared the groups 2 and 8 years later.
Findings 62 patients (18%) reported NDE, of whom 41 (12%) described a core
experience. Occurrence of the experience was not associated with duration
of cardiac
arrest or unconsciousness, medication, or fear of death before cardiac
arrest. Frequency
of NDE was affected by how we defined NDE, the prospective nature of the
research in
older cardiac patients, age, surviving cardiac arrest in first myocardial
infarction, more
than one cardiopulmonary resuscitation (CPR) during stay in hospital, previous
NDE, and
memory problems after prolonged CPR. Depth of the experience was affected
by sex,
surviving CPR outside hospital, and fear before cardiac arrest. Significantly
more patients
who had an NDE, especially a deep experience, died within 30 days of CPR
(p<0·0001).
The process of transformation after NDE took several years, and differed
from those of
patients who survived cardiac arrest without NDE.
Interpretation We do not know why so few cardiac patients report NDE after
CPR,
although age plays a part. With a purely physiological explanation such
as cerebral
anoxia for the experience, most patients who have been clinically dead
should report one.
Lancet 2001; 358: 2039-45
See Commentary
Introduction
Some people who have survived a life-threatening crisis report an extraordinary
experience. Near-death experience (NDE) occurs with increasing frequency
because of
improved survival rates resulting from modern techniques of resuscitation.
The content of
NDE and the effects on patients seem similar worldwide, across all cultures
and times.
The subjective nature and absence of a frame of reference for this experience
lead to
individual, cultural, and religious factors determining the vocabulary
used to describe and
interpret the 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 resulting from traumatic brain
damage,
intracerebral haemorrhage or cerebral infarction, attempted suicide, near-drowning
or
asphyxia, and apnoea. Such experiences are also reported by patients with
serious but
not immediately life-threatening diseases, in those with serious depression,
or without
clear cause in fully conscious people. Similar experiences to near-death
ones can occur
during the terminal phase of illness, and are called deathbed visions.
Identical
experiences to NDE, so-called fear-death experiences, are mainly reported
after
situations in which death seemed unavoidable: serious traffic accidents,
mountaineering
accidents, or isolation such as with shipwreck.
Several theories on the origin of NDE have been proposed. Some think the
experience is
caused by physiological changes in the brain, such as brain cells dying
as a result of
cerebral anoxia.2-4 Other theories encompass a psychological reaction to
approaching
death,5 or a combination of such reaction and anoxia.6 Such experiences
could also be
linked to a changing state of consciousness (transcendence), in which perception,
cognitive functioning, emotion, and sense of identity function independently
from normal
body-linked waking consciousness.7 People who have had an NDE are psychologically
healthy, although some show non-pathological signs of dissociation.7 Such
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 retrospective and very selective with respect
to
patients. In retrospective studies, 5-10 years can elapse between occurrence
of the
experience and its investigation, which often prevents accurate assessment
of
physiological and pharmacological factors. In retrospective studies, between
43%8 and
48%1 of adults and up to 85% of children10 who had a life-threatening illness
were
estimated to have had an NDE. A random investigation of more than 2000
Germans
showed 4·3% to have had an NDE at a mean age of 22 years.11 Differences
in estimates
of frequency and uncertainty as to causes of this experience result from
varying
definitions of the phenomenon, and from inadequate methods of research.12
Patients'
transformational processes after an NDE are very similar1,3,13-16 and encompass
life-changing insight, heightened intuition, and disappearance of fear
of death.
Assimilation and acceptance of these changes is thought to take at least
several
years.15
We did a prospective study to calculate the frequency of NDE in patients
after cardiac
arrest (an objective critical medical situation), and establish factors
that affected the
frequency, content, and depth of the experience. We also did a longitudinal
study to
assess the effect of time, memory, and suppression mechanisms on the process
of
transformation after NDE, and to reaffirm the content and allow further
study of the
experience. We also proposed to reassess theories on the cause and content
of NDE.
Methods
Patients
We included consecutive patients who were successfully resuscitated in
coronary care
units in ten Dutch hospitals during a research period varying between hospitals
from 4
months to nearly 4 years (1988-92). The research period varied because
of the
requirement that all consecutive patients who had undergone successful
cardiopulmonary resuscitation (CPR) were included. If this standard was
not met we
ended research in that hospital. All patients had been clinically dead,
which we
established mainly by electrocardiogram records. All patients gave written
informed
consent. We obtained ethics committee approval.
Procedures
We defined NDE as the reported memory 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, deceased relatives, or a life review.
We defined
clinical death as a period of unconsciousness caused by insufficient blood
supply to the
brain because of inadequate blood circulation, breathing, or both. If,
in this situation, CPR
is not started within 5-10 min, irreparable damage is done to the brain
and the patient will
die.
We did a short standardised interview with sufficiently well patients within
a few days of
resuscitation. We asked whether patients recollected the period of unconsciousness,
and what they recalled. Three researchers coded the experiences according
to the
weighted core experience index.1 In this scoring system, depth of NDE is
measured with
weighted scores assigned to elements of the content of the experience.
Scores between
1 and 5 denote superficial NDE, but we included these events because all
patients
underwent transformational changes as well. Scores of 6 or more denote
core
experiences, and scores of 10 or greater are deep experiences. We also
recorded date
of cardiac arrest, date of interview, sex, age, religion, standard of education
reached,
whether the patient had previously experienced NDE, previously heard of
NDE, whether
CPR took place inside or outside hospital, previous myocardial infarction,
and how many
times the patient had been resuscitated during their stay in hospital.
We estimated
duration of circulatory arrest and unconsciousness, and noted whether artificial
respiration by intubation took place. We also recorded type and dose of
drugs before,
during, and after the crisis, and assessed possible memory problems at
interview after
lengthy or difficult resuscitation. We classed patients resuscitated during
electrophysiological stimulation separately.
We did standardised and taped interviews with participants a mean of 2
years after CPR.
Patients also completed a life-change inventory.16 The questionnaire addressed
self-image, concern with others, materialism and social issues, religious
beliefs and
spirituality, and attitude towards death. Participants answered 34 questions
with a
five-point scale indicating whether and to what degree they had changed.
After 8 years,
surviving patients and their partners were interviewed again with the life-change
inventory, and also completed a medical and psychological questionnaire
for cardiac
patients (from the Dutch Heart Foundation), the Utrecht coping list, the
sense of
coherence inquiry, and a scale for depression. These extra questionnaires
were deemed
necessary for qualitative analysis because of the reduced number of respondents
who
survived to 8 years follow-up. Our control group consisted of resuscitated
patients who
had not reported an NDE. We matched controls with patients who had had
an NDE by
age, sex, and time interval between CPR and the second and third interviews.
Statistical analysis
We assessed causal factors for NDE with the Pearson 2 test for categorical
and t test
for ratio-scaled factors. Factors affecting depth of NDE were analysed
with the
Mann-Whitney test for categorical factors, and with Spearman's coefficient
of rank
correlation for ratio-scaled factors. Links between NDE and altered scores
for questions
from the life-change inventory were assessed with the Mann-Whitney test.
The sums of
the individual scores were used to compare the responses to the life-change
inventory
in the second and third interview. Because few causes or relations exist
for NDE, the null
hypotheses are the absence of factors. Hence, all tests were two-tailed
with significance
shown by p values less than 0·05.
Results
Patients
We included 344 patients who had undergone 509 successful resuscitations.
Mean age
at resuscitation was 62·2 years (SD 12·2), and ranged from
26 to 92 years. 251 patients
were men (73%) and 93 were women (27%). Women were significantly older
than men (66
vs 61 years, p=0·005).The ratio of men to women was 57/43 for those
older than 70 years,
whereas at younger ages it was 80/20. 14 (4%) patients had had a previous
NDE. We
interviewed 248 (74%) patients within 5 days after CPR. Some demographic
questions
from the first interview had too many values missing for reliable statistical
analysis, so
data from the second interview were used. Of the 74 patients whom we interviewed
at
2-year follow-up, 42 (57%) had previously heard of NDE, 53 (72%) were religious,
25
(34%) had left education aged 12 years, and 49 (66%) had been educated
until aged at
least 16 years.
296 (86%) of all 344 patients had had a first myocardial infarction and
48 (14%) had
undergone more than one infarction. Nearly all patients with acute myocardial
infarction
were treated with fentanyl, a synthetic opiod antagonist; thalamonal, a
combined
preparation of fentanyl with dehydrobenzperidol that has an antipsychotic
and sedative
effect; or both. 45 (13%) patients also received sedative drugs such as
diazepam or
oxazepam, and 38 (11%) were given strong sedatives such as midazolam (for
intubation),
or haloperidol for cerebral unrest during or after long-lasting unconsciousness.
234 (68%) patients were successfully resuscitated within hospital. 190
(81%) of these
patients were resuscitated within 2 min of circulatory arrest, and unconsciousness
lasted
less than 5 min in 187 (80%). 30 patients were resuscitated during electrophysiological
stimulation; these patients all underwent less than 1 min of circulatory
arrest and less
than 2 min of unconsciousness. This group were only given 5 mg of diazepam
about 1 h
before electrophysiological stimulation.
101 (29%) patients survived CPR outside hospital, and nine (3%) were resuscitated
both
within and outside hospital. Of these 110 patients, 88 (80%) had more than
2 min of
circulatory arrest, and 62 (56%) were unconscious for more than 10 min.
All people with
brief cardiac arrest and who were resuscitated outside hospital were resuscitated
in an
ambulance. Only 12 (9%) patients survived a circulatory arrest that lasted
longer than 10
min. 36% (123) of all patients were unconsciousness for longer than 60
min, 37 of these
patients needed artificial respiration through intubation. Intubated patients
received high
doses of strong sedatives and were interviewed later than other patients;
most were still
in a weakened physical condition at the time of first interview and 24
showed memory
defects. Significantly more younger than older patients survived long-lasting
unconsciousness following difficult CPR (p=0·005).
Prospective findings
62 (18%) patients reported some recollection of the time of clinical death
(table 1). Of
these patients, 21 (6% of total) had a superficial NDE and 41 (12%) had
a core
experience. 23 of the core group (7% of total) reported a deep or very
deep NDE.
Therefore, of 509 resuscitations, 12% resulted in NDE and 8% in core experiences.
Table
2 shows the frequencies of ten elements of NDE.1 No patients reported distressing
or
frightening NDE.
WCEI score*
n
A No memory
0
282 (82%)
B Some recollection
1-5
21 (6%)
C Moderately deep NDE
6-9
18 (5%)
D Deep NDE
10-14
17 (5%)
E Very deep NDE
15-19
6 (2%)
WCEI=weighted core experience index. NDE=near-death experience. *A=no NDE,
B=superficial NDE, C/D/E=core NDE.
Table 1: Distribution of the 344 patients in five WCEI classes*
Elements of NDE1
Frequency (n=62)
1 Awareness of being dead
31 (50%)
2 Positive emotions
35 (56%)
3 Out of body experience
15 (24%)
4 Moving through a tunnel
19 (31%)
5 Communication with light
14 (23%)
6 Observation of colours
14 (23%)
7 Observation of a celestial landscape
18 (29%)
8 Meeting with deceased persons
20 (32%)
9 Life review
8 (13%)
10 Presence of border
5 (8%)
NDE=near-death experience.
Table 2: Frequency of ten elements of NDE
During the pilot phase in one of the hospitals, a coronary-care-unit nurse
reported a
veridical out-of-body experience of a resuscitated patient:
"During a night shift an ambulance brings in a 44-year-old cyanotic, comatose
man into
the coronary care unit. He had been found about an hour before in a meadow
by
passers-by. After admission, he receives artificial respiration without
intubation, while
heart massage and defibrillation are also applied. When we want to intubate
the patient,
he turns out to have dentures in his mouth. I remove these upper dentures
and put them
onto the 'crash car'. Meanwhile, we continue extensive CPR. After about
an hour and a
half the patient has sufficient heart rhythm and blood pressure, but he
is still ventilated
and intubated, and he is still comatose. He is transferred to the intensive
care unit to
continue the necessary artificial respiration. Only after more than a week
do I meet again
with the patient, who is by now back on the cardiac ward. I distribute
his medication. The
moment he sees me he says: 'Oh, that nurse knows where my dentures are'.
I am very
surprised. Then he elucidates: 'Yes, you were there when I was brought
into hospital and
you took my dentures out of my mouth and put them onto that car, it had
all these bottles
on it and there was this sliding drawer underneath and there you put my
teeth.' I was
especially amazed because I remembered this happening while the man was
in deep
coma and in the process of CPR. When I asked further, it appeared the man
had seen
himself lying in bed, that he had perceived from above how nurses and doctors
had been
busy with CPR. He was also able to describe correctly and in detail the
small room in
which he had been resuscitated as well as the appearance of those present
like myself.
At the time that he observed the situation he had been very much afraid
that we would
stop CPR and that he would die. And it is true that we had been very negative
about the
patient's prognosis due to his very poor medical condition when admitted.
The patient
tells me that he desperately and unsuccessfully tried to make it clear
to us that he was
still alive and that we should continue CPR. He is deeply impressed by
his experience
and says he is no longer afraid of death. 4 weeks later he left hospital
as a healthy man."
Table 3 shows relations between demographic, medical, pharmacological,
and
psychological factors and the frequency and depth of NDE. No medical, pharmacological,
or psychological factor affected the frequency of the experience. People
younger than 60
years had NDE more often than older people (p=0·012), and women,
who were
significantly older than men, had more frequent deep experiences than men
(p=0·011)
(table 3). Increased frequency of experiences in patients who survived
cardiac arrest in
first myocardial infarction, and deeper experiences in patients who survived
CPR outside
hospital could have resulted from differences in age. Both these groups
of patients were
younger than other patients, though the age differences were not significant
(p=0·05 and
0·07, respectively).
Frequency of NDE
Depth
NDE
No NDE
p
of NDE
(n=62)
(n=282)
(n=62)
Categorical factors
Demographic
Women
13 (21%)
80 (28%)
NS
0·011
Age* <60 years
32 (52%)
96 (34%)
0·012
NS
Religion? (yes)
26 (70%)
27 (73% )
NS
NS
Education?? Elementary
10 (27%)
15 (43%)
NS
NS
Medical
Intubation
6 (10%)
31 (11%)
NS
NS
Electrophysiological
8 (13%)
22 (8%)
NS
NS
stimulation
First myocardial
60 (97%)
236 (84%)
0·013
NS
infarction
CPR outside hospital§
13 (21%)
88 (32%)
NS
0·027
Memory defect after
1 (2%)
40 (14%)
0·011
NS
lengthy CPR
Death within 30 days
13 (21%)
24 (9%)
0·008
0·017
Pharmacological
Extra medication
17 (27%)
70 (25%)
NS
NS
Psychological
Fear before CPR?§
4 (13%)
2 (6%)
NS
0·045
Previous NDE
6 (10%)
8 (3%)
0·035
NS
Foreknowledge of NDE?
22 (60%)
20 (54%)
NS
NS
Ratio-scaled factors
Demographic
Age (mean [SD], years)*
58·8 (13·4)
63·5 (11·8)
0·006
NS
Medical
Duration of cardiac
4·0 (5·2)
3·7 (3·9)
NS
NS
arrest (mean [SD], min)
Duration of
66·1 (269·5)
118·3 (355·5)
NS
NS
unconsciousness
(mean [SD], min)
Number of CPRs (SD)
2·1 (2·5)
1·4 (1·2)
0·029
NS
Data are number (%) unless otherwise indicated. CPR=cardiopulmonary resuscitation.
NS=not significant (p>0·05). *3 missing values. ?n=74 (data from
2nd interview, 35
NDE, 39 no NDE). ?2 missing values. §10 missing values.
Table 3: Factors affecting frequency and depth of near-death experience
(NDE)
Lengthy CPR can sometimes induce loss of memory and patients thus affected
reported
significantly fewer NDEs than others (table 3). No relation was found between
frequency of
NDE and the time between CPR and the first interview (range 1-70 days).
Mortality during
or shortly after stay in hospital in patients who had an NDE was significantly
higher than in
patients who did not report an NDE (13/62 patients [21%] vs 24/282 [9%],
p=0·008), and
this difference was even more marked in patients who reported a deep experience
(10/23
[43%] vs 24/282 [9%], p<0·0001).
Longitudinal findings
At 2-year follow-up, 19 of the 62 patients with NDE had died and six refused
to be
interviewed. Thus, we were able to interview 37 patients for the second
time. All patients
were able to retell their experience almost exactly. Of the 17 patients
who had low scores
in the first interview (superficial NDE), seven had unchanged low scores,
and four
probably had, in retrospect, an NDE that consisted only of positive emotions
(score 1).
Six patients had not in fact had an NDE after all, which was probably because
of our wide
definition of NDE at the first interview.
We selected a control group, matched for age, sex, and time since cardiac
arrest, from
the 282 patients who had not had NDE. We contacted 75 of these patients
to obtain 37
survivors who agreed to be interviewed. Two controls reported an NDE consisting
only of
positive emotions, and two a core experience. The first interview after
CPR might have
been too soon for these four patients (1% of total) to remember their NDE,
or to be willing
or able to describe the experience. We were therefore able to interview
35 patients who
had had an affirmed NDE, and 39 patients who had not.
Only six of the 74 patients that we interviewed at 2 years said they were
afraid before CPR
(table 3). Four of these six had deep NDE (p=0·045, table 3). Most
patients were not
afraid before CPR, as the arrest happened too suddenly and unexpectedly
to allow time
for fear.
Significant differences in answers to 13 of the 34 items in the life-change
inventory
between people with and without an NDE are shown in table 4. For instance,
people who
had NDE had a significant increase in belief in an afterlife and decrease
in fear of death
compared with people who had not had this experience. Depth of NDE was
linked to high
scores in spiritual items such as interest in the meaning of one's own
life, and social
items such as showing love and accepting others. The 13 patients who had
superficial
NDE underwent the same specific transformational changes as those who had
a core
experience.
LIfe-change inventory questionnaire
p
Social attitude
Showing own feelings
0·034
Acceptance of others*
0·012
More loving, empathic*
0·002
Understanding others*
0·003
Involvement in family*
0·008
Religious attitude
Understand purpose of life*
0·020
Sense inner meaning of life*
0·028
Interest in spirituality*
0·035
Attitude to death
Fear of death*
0·009
Belief in life after death*
0·007
Others
Interest in meaning of life
0·020
Understanding oneself
0·019
Appreciation of ordinary things
0·0001
NDE=near-death experience. 35 patients had NDE, 39 had not had NDE. 1 value
missing for patients wih NDE in all categories; *2 values missing for patients
with NDE
(ie, n=33).
Table 4: Significant differences in life-change inventory-scores16 of patients
with and without NDE at 2-year follow-up
8-year follow-up included 23 patients with an NDE that had been affirmed
at 2-year
follow-up. 11 patients had died and one could not be interviewed. Patients
could still
recall their NDE almost exactly. Of the patients without an NDE at 2-year
follow-up, 20
had died and four patients could not be interviewed (for reasons such as
dementia and
long stay in hospital), which left 15 patients without an NDE to take part
in the third
interview.
All patients, including those who did not have NDE, had gone through a
positive change
and were more self-assured, socially aware, and religious than before.
Also, people who
did not have NDE had become more emotionally affected, and in some, fear
of death had
decreased more than at 2-year follow-up. Their interest in spirituality
had strongly
decreased. Most patients who did not have NDE did not believe in a life
after death at
2-year or 8-year follow-up (table 5). People with NDE had a much more complex
coping
process: they had become more emotionally vulnerable and empathic, and
often there
was evidence of increased intuitive feelings. Most of this group did not
show any fear of
death and strongly believed in an afterlife. Positive changes were more
apparent at 8
years than at 2 years of follow-up.
Life-change inventory
2-year follow-up
8-year follow-up
questionnaire
NDE
no NDE
NDE
no NDE
(n=23)
(n=15)
(n=23)
(n=15)
Social attitude
Showing own feelings
42
16
78
58
Acceptance of others
42
16
78
41
More loving, empathic
52
25
68
50
Understanding others
36
8
73
75
Involvement in family
47
33
78
58
Religious attitude
Understand purpose of life
52
33
57
66
Sense inner meaning of life
52
25
57
25
Interest in spirituality
15
-8
42
-41
Attitude to death
Fear of death
-47
-16
-63
-41
Belief in life after death
36
16
42
16
Others
Interest in meaning of life
52
33
89
66
Understanding oneself
58
8
63
58
Appreciation of ordinary things
78
41
84
50
NDE=near-death experience. The sums of all individual scores per item are
reported
in the same 38 patients who had both follow-up interviews. Participants
responded in a
five-point scale indicating whether and to what degree they had changed:
strongly
increased (+2), somewhat increased (+1), no change (0), somewhat decreased
(-1),
and strongly decreased (-2). Only in the reported 13 (of 34) items in this
table were
significant differences found in life-change scores in the interview after
2 years (table
4).
Table 5: Total sum of individual life-change inventory scores16 of patients
at
2-year and 8-year follow-up
Discussion
Our results show that medical factors cannot account for occurrence of
NDE; although all
patients had been clinically dead, most did not have NDE. Furthermore,
seriousness of
the crisis was not related to occurrence or depth of the experience. If
purely physiological
factors resulting from cerebral anoxia caused NDE, most of our patients
should have had
this experience. Patients' medication was also unrelated to frequency of
NDE.
Psychological factors are unlikely to be important as fear was not associated
with NDE.
The 18% frequency of NDE that we noted is lower than reported in retrospective
studies,1,8 which could be because our prospective study design prevented
self-selection of patients. Our frequency of NDE is low despite our wide
definition of the
experience. Only 12% of patients had a core NDE, and this figure might
be an
overestimate. When we analysed our results, we noted that one hospital
that participated
in the study for nearly 4 years, and from which 137 patients were included,
reported a
significantly (p=0·01) lower percentage of NDE (8%), and significantly
(p=0·05) fewer deep
experiences. Therefore, possibly some selection of patients occurred in
the other
hospitals, which sometimes only took part for a few months. In a prospective
study17 with
the same design as ours, 6% of 63 survivors of cardiac arrest reported
a core
experience, and another 5% had memories with features of an NDE (low score
in our
study); thus, with our wide definition of the experience, 11% of these
patients reported an
NDE. Therefore, true frequency of the experience is likely to be about
10%, or 5% if based
on number of resuscitations rather than number of resuscitated patients.
Patients who
survive several CPRs in hospital have a significantly higher chance of
NDE (table 3).
We noted that the frequency of NDE was higher in people younger than 60
years than in
older people. In other studies, mean age at NDE is lower than our estimate
(62·2 years)
and the frequency of the experience is higher. Morse10 saw 85% NDE in children,
Ring1
noted 48% NDE in people with a mean age of 37 years, and Sabom8 saw 43%
NDE in
people with a mean age of 49 years; thus, age and the frequency of the
experience seem
to be associated. Other retrospective studies have noted a younger mean
age for NDE:
32 years,9 29 years,6 and 22 years.11 Cardiac arrest was the cause of the
experience in
most patients in Sabom's8 study, whereas this was the case in only a low
percentage of
patients in other work. We saw that people surviving CPR outside hospital
(who
underwent deeper NDE than other patients) tended to be younger, as were
those who
survived cardiac arrest in a first myocardial infarction (more frequent
NDE), which
indicates that age was probably decisive in the significant relation noted
with those
factors.
In a study of mortality in patients after resuscitation outside hospital,18
chances of
survival increased in people younger than 60 years and in those undergoing
first
myocardial infarction, which corresponds with our findings. Older people
have a smaller
chance of cerebral recovery after difficult and complicated resuscitation
after cardiac
arrest. Younger patients have a better chance of surviving a cardiac arrest,
and thus, to
describe their experience. In a study of 11 patients after CPR, the person
that had an
NDE was significantly younger than other patients who did not have such
an
experience.19 Greyson7 also noted a higher frequency of NDE and significantly
deeper
experiences at younger ages, as did Ring.1
Good short-term memory seems to be essential for remembering NDE. Patients
with
memory defects after prolonged resuscitation reported fewer experiences
than other
patients in our study. Forgetting or repressing such experiences in the
first days after
CPR was unlikely to have occurred in the remaining patients, because no
relation was
found between frequency of NDE and date of first interview. However, at
2-year follow-up,
two patients remembered a core NDE and two an NDE that consisted of only
positive
emotions that they had not reported shortly after CPR, presumably because
of memory
defects at that time. It is remarkable that people could recall their NDE
almost exactly
after 2 and 8 years.
Unlike our results, an inverse correlation between foreknowledge and frequency
of NDE
has been shown.1,8 Our finding that women have deeper experiences than
men has been
confirmed in two other studies,1,7 although in one,7 only in those cases
in which women
had an NDE resulting from disease.
The elements of NDE that we noted (table 2) correspond with those in other
studies
based on Ring's1 classification. Greyson20 constructed the NDE scale differently
to
Ring,1 but both scoring systems are strongly correlated (r=0·90).
Yet, reliable
comparisons are nearly impossible between retrospective studies that included
selection
of patients, unreliable medical records, and used different criteria for
NDE,12 and our
prospective study.
Our longitudinal follow-up research into transformational processes after
NDE confirms
the transformation described by many others.1-3,8,10,13-16,21 Several of
these
investigations included a control group to enable study of differences
in transformation,14
but in our research, patients were interviewed three times during 8 years,
with a matched
control group. Our findings show that this process of change 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 response
to NDE, which
leads individuals to deny or suppress their experience for fear of rejection
or ridicule.
Thus, social conditioning causes NDE to be traumatic, although in itself
it is not a
psychotraumatic experience. As a result, the effects of the experience
can be delayed for
years, and only gradually and with difficulty is an NDE accepted and integrated.
Furthermore, the longlasting transformational effects of an experience
that lasts for only a
few minutes of cardiac arrest is a surprising and unexpected finding.
One limitation of our study is that our study group were all Dutch cardiac
patients, who
were generally older than groups in other studies. Therefore, our frequency
of NDE might
not be representative of all cases--eg, a higher frequency could be expected
with
younger samples, or rates might vary in other populations. Also, the rates
for NDE could
differ in people who survive near-death episodes that come about by different
causes,
such as near drowning, near fatal car crashes with cerebral trauma, and
electrocution.
However, rigorous prospective studies would be almost impossible in many
such cases.
Several theories have been proposed to explain NDE. We did not show that
psychological, neurophysiological, or physiological factors caused these
experiences
after cardiac arrest. Sabom22 mentions a young American woman who had complications
during brain surgery for a cerebral aneurysm. The EEG of her cortex and
brainstem had
become totally flat. After the operation, which was eventually successful,
this patient
proved to have had a very deep NDE, including an out-of-body experience,
with
subsequently verified observations during the period of the flat EEG.
And yet, neurophysiological processes must play some part in NDE. Similar
experiences
can be induced through electrical stimulation of the temporal lobe (and
hence of the
hippocampus) during neurosurgery for epilepsy,23 with high carbon dioxide
levels
(hypercarbia),24 and in decreased cerebral perfusion resulting in local
cerebral hypoxia
as in rapid acceleration during training of fighter pilots,25 or as in
hyperventilation followed
by valsalva manoeuvre.4 Ketamine-induced experiences resulting from blockage
of the
NMDA receptor,26 and the role of endorphin, serotonin, and enkephalin have
also been
mentioned,27 as have near-death-like experiences after the use of LSD,28
psilocarpine,
and mescaline.21 These induced experiences can consist of unconsciousness,
out-of-body experiences, and perception of light or flashes of recollection
from the past.
These recollections, however, consist of fragmented and random memories
unlike the
panoramic life-review that can occur in NDE. Further, transformational
processes with
changing life-insight and disappearance of fear of death are rarely reported
after induced
experiences.
Thus, induced experiences are not identical to NDE, and so, besides age,
an unknown
mechanism causes NDE by stimulation of neurophysiological and neurohumoral
processes at a subcellular level in the brain in only a few cases during
a critical situation
such as clinical death. These processes might also determine whether the
experience
reaches consciousness and can be recollected.
With lack of evidence for any other theories for NDE, the thus far assumed,
but never
proven, concept that consciousness and memories are localised in the brain
should be
discussed. How could a clear consciousness outside one's body be experienced
at the
moment that the brain no longer functions during a period of clinical death
with flat
EEG?22 Also, in cardiac arrest the EEG usually becomes flat in most cases
within about
10 s from onset of syncope.29,30 Furthermore, blind people have described
veridical
perception during out-of-body experiences at the time of this experience.31
NDE pushes
at the limits of medical ideas about the range of human consciousness and
the
mind-brain relation.
Another theory holds that NDE might be a changing state of consciousness
(transcendence), in which identity, cognition, and emotion function independently
from the
unconscious body, but retain the possibility of non-sensory perception.7,8,22,28,31
Research should be concentrated on the effort to explain scientifically
the occurrence
and content of NDE. Research should be focused on certain specific elements
of NDE,
such as out-of-body experiences and other verifiable aspects. Finally,
the theory and
background of transcendence should be included as a part of an explanatory
framework
for these experiences.
Contributors
Pim van Lommel coordinated the first interviews and was responsible for
collecting all
demographic, medical, and pharmacological data. Pim van Lommel, Ruud van
Wees, and
Vincent Meyers rated the first interview. Ruud van Wees and Vincent Meyers
coordinated the second interviews. Ruud van Wees did statistical analysis
of the first and
second interviews. Ingrid Elfferich did the third interviews and analysed
these results.
Acknowledgments
We thank nursing and medical staff of the hospitals involved in the research;
volunteers
of the International Association of Near Death Studies; IANDS-Netherlands;
Merkawah
Foundation for arranging interviews, and typing the second and third interviews;
Martin
Meyers for help with translation; and Kenneth Ring and Bruce Greyson for
review of the
article.
References
1 Ring K. Life at death. A scientific investigation of the near- death
experience. New York:
Coward McCann and Geoghenan, 1980.
2 Blackmore S. Dying to live: science and the near-death experience. London:
Grafton--an imprint of Harper Collins Publishers, 1993.
3 Morse M. Transformed by the light. New York: Villard Books, 1990.
4 Lempert T, Bauer M, Schmidt D. Syncope and near-death experience.
Lancet
1994; 344: 829-30. [PubMed]
5 Appelby L. Near-death experience: analogous to other stress induced physiological
phenomena . BMJ 1989; 298: 976-77. [PubMed]
6 Owens JE, Cook EW, Stevenson I. Features of "near-death experience" in
relation to
whether or not patients were near death . Lancet 1990; 336: 1175-77. [PubMed]
7 Greyson B. Dissociation in people who have near-death experiences: out
of their
bodies or out of their minds? Lancet 2000; 355: 460-63. [Text]
8 Sabom MB. Recollections of death: a medical investigation. New York:
Harper and Row,
1982.
9 Greyson B. Varieties of near-death experience.
Psychiatry 1993; 56: 390-99. [PubMed]
10 Morse M. Parting visions: a new scientific paradigm. In: Bailey LW,
Yates J, eds. The
near-death experience: a reader. New York and London: Routledge, 1996:
299-318.
11 Schmied I, Knoblaub H, Schnettler B. Todesnäheerfahrungen in Ost-
und
Westdeutschland--eine empirische Untersuchung. In: Knoblaub H, Soeffner
HG, eds.
Todesnähe: interdisziplinäre Zugänge zu einem außergewöhnlichen
Phänomen. Konstanz:
Universitätsverlag Konstanz, 1999: 217-50.
12 Greyson B. The incidence of near-death experiences. Med Psychiatry
1998; 1: 92-99. [PubMed]
13 Roberts G, Owen J. The near-death experience. Br J
Psychiatry 1988; 153: 607-17. [PubMed]
14 Groth-Marnat G, Summers R. Altered beliefs, attitudes and behaviors
following
near-death experiences. J Hum Psychol 1998; 38: 110-25.
[PubMed]
15 Atwater PMH. Coming back to life: the after-effects of the near-death
experience. New
York: Dodd, Mead and Company, 1988.
16 Ring K. Heading towards omega: in search of the meaning of the near-death
experience. New York: Quill William Morrow, 1984.
17 Parnia S, Waller DG, Yeates R, Fenwick P. A qualitative and quantitative
study of the
incidence, features and aetiology of near death experiences in cardiac
arrest survivors.
Resuscitation 2001; 48: 149-56. [PubMed]
18 Dickey W, Adgey AAJ. Mortality within hospital after resuscitation from
ventricular
fibrillation outside hospital. Br Heart J 1992; 67: 334-38.
[PubMed]
19 Schoenbeck SB, Hocutt GD. Near-death experiences in patients undergoing
cardio-pulmonary resuscitation. J Near-Death Studies 1991;
9: 211-18. [PubMed]
20 Greyson B. The near-death experience scale: construction, reliability
and validity. J
Nervous Mental Dis 1982; 171: 369-75. [PubMed]
21 Schröter-Kunhardt M. Nah--Todeserfahrungen aus psychiatrisch-neurologischer
Sicht. In: Knoblaub H, Soeffner HG, eds. Todesnähe: interdisziplinäre
Zugänge zu einem
außergewöhnlichen Phänomen. Konstanz: Universitätsverlag
Konstanz, 1999: 65-99.
22 Sabom MB. Light and death: one doctors fascinating account of near-death
experiences. Michigan: Zondervan Publishing House, 1998: 37-52.
23 Penfield W. The excitable cortex in conscious man. Liverpool: Liverpool
University
Press, 1958.
24 Meduna LT. Carbon dioxide therapy: a neuropsychological treatment of
nervous
disorders. Springfield: Charles C Thomas, 1950.
25 Whinnery JE, Whinnery AM. Acceleration-induced loss of consciousness.
Arch
Neurol 1990; 47: 764-76. [PubMed]
26 Jansen K. Neuroscience, ketamine and the near-death experience: the
role of
glutamate and the NMDA-receptor. In: Bailey LW, Yates J, eds. The near-death
experience: a reader. New York and London: Routledge, 1996: 265-82.
27 Greyson B. Biological aspects of near-death experiences. Perspect
Biol
Med 1998; 42: 14-32. [PubMed]
28 Grof S, Halifax J. The human encounter with death. New York: Dutton, 1977.
29 Clute HL, Levy WJ. Electroencephalographic changes during brief cardiac
arrest in
humans. Anesthesiology 1990; 73: 821-25. [PubMed]
30 Aminoff MJ, Scheinman MM, Griffing JC, Herre JM. Electrocerebral accompaniments
of syncope associated with malignant ventricular arrhythmias. Ann
Intern Med
1988; 108: 791-96. [PubMed]
31 Ring K, Cooper S. Mindsight: near-death and out-of-body experiences
in the blind.
Palo Alto: William James Center for Consciousness Studies, 1999.