Ketamine-induced „near-death experience‟ states in a sample
of 50 misusers.
Ornella Corazza (*) and Fabrizio Schifano (*)
(*) University of Hertfordshire, Pharmacy and Postgraduate Medical
Schools, Hatfield, Herts, AL10 9AB (UK).
Address for correspondence:
Dr Ornella Corazza
The Psychonaut Project
University of Hertfordshire
School of Pharmacy
College Lane Campus
AL10 9AB (UK)
Telephone: +44 (0)1707-289431
Fax: +44 (0)1707-284506
Mobile: +44 (0)7894 666 936
Increase in recreational ketamine use may be a cause for concern. We aimed
here at assessing, in a sample of ketamine misusers, concordance between the
typical near-death experience (NDE) features and the on-drug psychoactive
effects the subjects experienced. In 2003-2005, a sample of previous ketamine
misusers recollecting a ketamine-related NDE were recruited through snowballing
and screened with the means of the Greyson NDE Scale; 125 participants made
an initial contact with the researcher and 50 reported a minimum score of 7 at
the ‘Greyson NDE Scale’. Interviewees were in the range 21-66 years old; 27
participants (54%) were educated at BA level; 18 (36%) had an MSc and 5
(10%) a PhD. Eight (16%) interviewees had a definite religious background. An
average lifetime ketamine intake of 140 occasions was reported by the
interviewees, who typically presented with a polydrug, including cannabis and
MDMA/ecstasy, misuse history. In 45 (90%) cases, the NDE occurred during the
first few occasions of intake. Most frequent features of reported NDE states
included: altered perception of time (90%); strong sense of detaching from own
physical body (88%); and a sense of peace/joy (76% of subjects). Although
results here described were elicited from a self-selected, non randomized, limited
size sample of misusers, we suggest that recreational ketamine intake may be
associated with occurrence of near-death related states, and this may be a
reason for concern.
Key words: ketamine; drug misuse; near-death experiences (NDEs); out-of-
Ketamine: a phencyclidine (PCP) related, non-competitive, glutamate N-
Methyl-D-Aspartate receptor (NMDA) antagonist classified as a dissociative
anaesthetic. It is typically used in the UK in both Emergency Departments
and chronic pain clinics, but its recent increase in recreational misuse in
the clubbing scene may be a cause for concern.
Near-death experiences (NDEs): a range of clinical and non clinical events
are thought to be typically associated with NDE occurrence, including:
cardiac arrest; near-drowning and prolonged isolation/sensory deprivation.
Most frequently described features of an NDE include: a sense of joy,
peace, love; the detachment from own physical body; travelling along a
region of darkness towards a light at the end; visualization of past
Greyson NDE Scale: a validated and standardised 16-item questionnaire,
successfully used in previous studies to assess NDE core components in a
variety of medical patients.
(Spanish) Experiencias „cerca de la muerte‟ inducidas por Ketamina en
una muestra de 50 consumidores.
El aumento en el consumo ilícito de Ketamina es un hecho preocupante. El
objetivo del estudio consistió en valorar en una muestra de consumidores de
Ketamina la concordancia entre experiencias subjetivas de estar cercano a la
muerte y otros efectos psicoactivos bajo el efecto de la droga. Se reclutaron
participantes con dichas experiencias y fueron evaluados con la escala ‘Greyson
NDE’ entre 2003 y 2005. 125 participantes fueron contactados, de los cuales 50
puntuaron al menos 7 en dicha escala. Las edades de los sujetos estaban
comprendidas entre 21 y 66 años. 27 participantes (54%) poseían una
licenciatura universitaria, 18 (36%) habían hecho un Master y 5 (10%) tenían un
doctorado. 8 sujetos (16%) se identificaron con una creencia religiosa concreta.
Los muestrados reportaron una media de consumo total de 140 experiencias con
ketamina, presentando un perfil de politoxicomanía en la que el cannabis y el
éxtasis predominaban en su historia de consumo. En 45 casos (90%) la
experiencia de estar cerca de la muerte se asoció a las primeras ocasiones en que
la Ketamina fue consumida. Las características más típicas de esta experiencia
que fueron encontradas en la muestra estaban relacionadas con: percepción
alterada del tiempo (88%); una sensación vívida de morir y de distanciarse del
mundo físico (88%); una sensación de paz/regocijo (72%). Aunque los resultados
aquí descritos se recogieron a través de una muestra no aleatoria,
autoseleccionada y con un número limitado de participantes, los datos parecen
sugerir que el uso ilícito de Ketamina puede estar asociado con la ocurrencia de
estados subjetivos de estar cerca de la muerte. Tales datos son un resultado
Palabras Clave: ketamina; toxicomanía; experiencias cerca de la muerte;
(French) “Evaluation des „Expériences de Mort Imminente‟ engendrées
par l‟usage de la Kétamine chez un échantillon de 50 toxicomanes”
L’augmentation de l’usage de la Kétamine à des fins non-médicales peut être un
facteur d’inquiétude. Notre but était d’évaluer la concordance entre les
caractéristiques typiques de l’expérience de mort imminente (EMI) et les effets
psychoactifs du stupéfiant chez un échantillon de drogués à la Kétamine (ou
consommateurs de Kétamine). En 2003-2005, un échantillon d’anciens drogués à
la Kétamine a été constitué et examiné selon l’Echelle EMI de Greyson. Un
contact initial eut lieu entre 125 participants et le chercheur et 50 ont obtenu le
niveau minimum de 7 selon cette échelle. Les interviewés étaient âgés de 21 à 66
ans. 27 (54%) possédaient un diplôme universitaire;18 (36%) avaient une
Maitrise et 5 (10%) un Doctorat. Huit (16%) d’entre eux étaient membres d’une
religion définie. Les personnes interviewées rapportèrent avoir consommé la
Kétamine en moyenne 140 fois dans leur vie, ainsi que d’autres drogues dont le
cannabis et l’ecstasy. Dans 45 (90%) des cas l’état EMI eut lieu lors des toutes
premières consommations. Les caractéristiques les plus fréquentes de l’état EMI
comprennent: perception altérée du temps (90%); expérience de sortie de corps
(88%); extase/sensation d’apaisement (76% des sujets). Bien que les résultats
décrits ici soient issus d’un échantillonnage limité de toxicomanes volontaires,
non choisis au hasard, cette étude suggère que l’usage non-médical de la
Kétamine peut être associé à la survenance des états EMI et cela soulève des
Mots clés: Kétamine (ou spécial k); toxicomanie; expérience de mort imminente
(EMI); expérience de sortie de corps (ESC)
Ketamine is a phencyclidine (PCP) related, non-competitive,
glutamate N-Methyl-D-Aspartate receptor (NMDA) antagonist
classified as a dissociative anaesthetic. The term ‘dissociative’
suggests that the sensory loss and analgesia as well as amnesia is
not accompanied by actual loss of consciousness (Bonta 2003).
Ketamine causes mild stimulation of the cardiovascular system and
does not suppress respiration and gag reflex. Because of these
characteristics, ketamine has a good safety record (Wollf and
Winstock, 2006), being typically used in the UK in both Emergency
Departments and chronic pain clinics (Green et al. 1998; Sehdev et
al. 2006; Bell et al. 2006). Conversely, administration of the drug in
high doses can cause cardiovascular and respiratory toxicity (Smith
et al, 2002) and increase in unregulated use outside controlled
environments may be a cause for concern. Schifano et al (in press)
recently focused on ketamine misuse mortality figures (UK; 1993-
2006), extracted from various sources and identified 23 victims
(typically males, in the 25-44 age group) who self-administered
themselves with a miscellany of psychoactive compounds (including
ketamine) and alcohol. Ketamine was detected in 4 cases on its own
and they suggested that ketamine high safety profile should be
In the UK, lifetime prevalence of use in clubbers recently increased
from 25.5% to 39.8%, (McCambridge et al, 2007). Behind its
popularity a few reasons can be identified (Drugscope, 2005;
Morgan et al. 2004c), including both short (5-30 minutes after
intranasal administration) duration of action and low cost.
Recreational ketamine psychotropic effects (sometimes referred to
as the ‘K-hole’; Pomarol-Clotet et al, 2006) range from confusional
states, vivid dreams, hallucinations, flashbacks, referential thinking,
dissociation and depersonalization to psychotic experiences.
At sub-anaesthetic doses, ketamine intake has been anecdotally
described to be associated with effects somewhat similar to those
reported during a near-death experience (NDE; Greyson and
Stevenson 1980; Jansen 1989; Bonta 2003; French 2005).
Conversely, a vast range of clinical and non clinical events are
thought to be more typically associated with NDE occurrence,
including: cardiac arrest (van Lommel et al, 2001);
hypovolemic/septic/anaphylactic shock; intracerebral haemorrhage;
cerebral infarction; near-drowning or asphyxia; apnoea (for a
review, see Parnia et al. 2001); electro-stimulation of the temporal
lobe (Persinger 1983); and prolonged isolation/sensory deprivation
(Comer et al. 1967). Most frequently described features of an NDE
include (Moody 1975): (a) the ineffable nature of the experience;
(b) a sense of joy, peace, love; (c) the detachment from own
physical body (out-of-body experiences; Blanke et al. 2002; Sartori
2005); (d) travelling along a region of darkness towards a light at
the end; (e) visualization of past experiences, sometimes organized
into a life-review (Greyson and Stevenson 1980; Moody 1975); (f)
visions and communications with deceased relatives and friends or
‘beings of light’; (g) a decision to return to life; and (h) altered
perception of time. Ketamine effects and NDEs might bear some
level of resemblance at a neurobiological level as well. In fact, both
ketamine and NDEs involve events at glutamate N-methyl-D-
aspartate (NMDA) receptors (Bonta 2003; Jansen 1989; Fenwick
1997). However, it is still unclear if reported ketamine psychoactive
effects may appropriately fit into typically described features of an
NDE. As a consequence, we aimed here at assessing, in a sample of
recreational users, concordance between ketamine psychoactive
effects and classically described NDE features. This may help in
better understanding both the drug psychoactive effects and its
health related risks.
To develop the research sample, a snowballing technique was used.
For recruitment purposes of the first study subjects, an internal
email was sent by one of us (OC) to all undergraduate,
postgraduate and postdoctoral University of London students,
explaining the purpose of the research to be carried out and
redirecting those students who were willing to share their own
ketamine experiences to an ad-hoc website, which was available
throughout the research period (2003-5). An advice was made as
well via popular announcements and through a network of
informants, looking for retrospective accounts of ketamine
experience (s). Further study participants were identified from
among the already recruited participants’ acquaintances. If
respondents had both a previous recreational ketamine experience
and recollected what they believed to have been an NDE, they were
invited to fill in the ‘Greyson NDE Scale’ (Greyson 1983). This is a
validated and standardised 16-item questionnaire, successfully used
in previous studies to assess NDE core components in a variety of
medical patients (Parnia et. al 2001; Corazza, in press). Those 50
respondents who recollected a ketamine-related NDE and reported
as well a minimum score of 7 at the Greyson scale were invited for
an interview. Answers to the questionnaire were used as the basis
of the open ended interview, which enabled the interviewer to
explore themes and topics relevant to participants' individual
circumstances. Interviews were tape recorded and transcribed;
detailed notes were taken as well. Overall, 125 subjects made at
least an initial contact with the researcher and described online
their ketamine experience(s). After an initial screening, 60 subjects
were invited to fill in the Greyson scale and 10 of them did not
reach the cut off score. In those 10 cases, most of the psychoactive
experiences reported involved either vivid dreams or complex
auditory/visual hallucinations, but did not include any experiences
reminding of an NDE. Qualitative results were scrutinized with the
means of the content analysis; it was here assumed that words and
phrases mentioned most often were those reflecting the most
important topics highlighted by the interviewees (Krippendorf,
2004). Answers to open ended questions and communication
contents were categorized, classified and systematically analysed.
Interviews were always carried out in English, since subjects were
either fluent or native English speakers. All participants gave
informed written consent to participate to the study. The South
Oriental and African Studies, University of London, Ethics
Committee granted the study approval.
All participants (see Table 1 for both their background and drug
misuse history) had tried ketamine at least once in their lifetime.
(Please insert Table 1 about here)
Interestingly, in 45 (90%) cases, the NDE state occurred either
during the first 5 occasions of intake or during the first few
experiences after long spells of ketamine-free periods. On further
occasions of intake, ketamine was typically perceived as a
stimulant. In term of the Greyson NDE Scale (see Table 2), the
subjects’ perception of time seemed to be altered as typically
described during an NDE: 45 (90%) participants reported that
everything seemed to be happening at once, or that time lost all its
meaning, while 5 (10%) perceived a complete ‘absence of time’
during the experience.
(Please insert Table 2 about here)
The sense of dissociation from the physical body was experienced
by 44 subjects (88%), who claimed that they left their bodies and
existed outside it or that they lost awareness of their bodies.
Thirteen subjects (26%) clearly described a travel along a tunnel, or
through a spiral, with a brilliant light at the end or experienced a
more general sense of light, or of flashing lights. Fifteen (30%)
participants somewhat met with a ‘being’, or heard a definite voice
of mystical or unearthly nature. An infrequently described feature
was the so called ‘life review’. Twelve (24%) subjects reported that
they were able to either vividly ‘review’ past events, or felt that
their past ‘flashed before them, out of control’. Furthermore, 10
(20%) subjects reported that during their experience they were
‘aware of things going on elsewhere’, as if by extra-sensory
perceptions. At the question ‘Did you suddenly seem to understand
everything?’ most interviewees (26; 52%), answered that they
achieved ‘a total understanding of the universe’. Only 4 (8%)
participants approached a sort of ‘barrier’ or ‘a point of no return’,
which was described as ‘the limit between earthly life and the next
life’. This could have been an edge, a wall, or a river, amongst other
patterns. Thirty-six (72%) respondents experienced an ineffable
sense of peace and pleasantness, and 38 (76%) subjects described
an ‘incredible joy’.
It is suggested here that recreational ketamine misuse may be
associated with occurrence of NDE states, at least in a self-selected
group of misusers. NDEs typically occurred during the first few
occasions of ketamine intake, suggesting that individuals who have
developed higher tolerance levels may be at smaller risk.
Results here described were elicited from a self-selected, non
randomized, limited size sample of ketamine misusers and findings
identified may not allow their generalizability. More attention was
given to the experiential (qualitative) aspects of the accounts,
rather than to a quantitative component. However, present
approach may have increased the understanding of the ketamine
effects among misusers. All the subjects’ accounts dealt with
memories of a sometimes remote event, and one could wonder how
much ketamine-induced memory disturbances (Morgan et al.
2004a, 2004b) may have biased respondents’ recollection of their
drug-induced NDE experience. Furthermore, although all the
interviewees claimed that the experience was the result of a
ketamine monointoxication, most subjects were actually polydrug
misusers. Only prospective, double-blind vs placebo, clinical studies
with ketamine-naïve human volunteers may assess the possible role
of subjects’ personality in shaping the subjectively experienced NDE
states. On the other hand, prospective studies with ketamine
dosages large enough to induce a dissociative state could have
raised ethical concerns (Perry et al, 2007). Furthermore, most
interviewees were highly educated individuals (46% had either a
Master or a PhD degree); this may have overestimated here the
real occurrence of NDEs among ketamine users. Further biases may
have arisen in relation to some participants not having been
interviewed in their native language. On the other hand, the main
problem here was indeed given by the somewhat ‘ineffability’ of the
experience, difficult to be translated into any words of any
language. Finally, since interviews had not been carried out in close
proximity of a recent ketamine intoxication, no toxicological tests
were here carried out to back up the interviewees’ allegations, and
one could not rule out that other drugs (i.e.: cannabis) had not
recently been self-administered (Jansen 2001).
Future studies should be carried out in larger samples of ketamine
misusers, and results should be systematically compared with those
emerged in the related field of near-death studies in medical
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Table 1: Background characteristics and drug misuse history
of those 50 interviewees who reported an NDE-related state
in association with a ketamine misuse occasion of intake
Age range 19-66 years old
origin Germany: 29; 58%); USA (5; 10%) and Japan (1 subject).
Civil status Mostly single: 94%
Presence of a
religious belief practising members of their faith.
intake than 5 occasions and 7 (14%) between 5 and 10 occasions.
Most (58%) were more experienced ketamine users, having
taken it on up to 2,000 occasions. Overall, ketamine had
been taken on an average of 140 occasions. Typically,
ketamine was taken intranasally (62%), but 9 (18%)
participants had injected it intramuscularly; 8 (16%)
intravenously, and 2 (4%) subjects were used to smoke it.
Ketamine typical dosage per occasion of use ranged between
20 and 150 mg. In 15 (30%) cases, ketamine last occasion of
use occurred within the last month, but no subjects had
taken it within the last week.
male: 52%; female: 48%
UK (15; 30%), continental Europe (Italy, Spain and
Most were either in full-time employment (42%) or students
27 (54%) had a BA; 18 (36%) had an MSc; 5 (10%) a PhD.
8 (16%) had a religious (i.e.: Christian: 4 subjects; Jewish:
2; Buddhist: 1; Muslim: 1) belief. Only 2 subjects were
All subjects had tried ketamine at least once in their lifetime;
14 (28%) reported having consumed the substance on less
All subjects had previously experienced with both cannabis
and MDMA/ecstasy at least once in their lifetime; 17(34%)
had tried amphetamines/‘speed’; 46 (92%) cocaine; 48
(96%) LSD; 43 (86%) magic mushrooms; and 8 (16%)
Most interviewees appeared to be intelligent, smart, and well
settled in their environment. Furthermore, they were able to
make and maintain meaningful and long term
friendly/affective relationships. A few subjects used both
ketamine and the other drugs recreationally, whilst clubbing.
Conversely, most subjects reported that they had not
developed any dependence on ketamine, which had been
typically used to increase the users’ level of ‘intellectual
creativity’. From the ‘spiritual’ point of view, the ketamine
intake itself was described by some as an ‘enriching’
Table 2: Greyson Scale results of those 50 interviewees who
reported an NDE-related state in association with a ketamine
misuse occasion of intake
(please note that not all subjects answered items 2, 7 and 10 of the scale)
1. Did time seem to be speeding up?
2. Were your 'visions' accelerated?
3. Did you experience a ‘life review’ of
scenes from your past?
4. Did you seem to understand
5. Did you experience a sense of peace
6. Did you experience feelings of joy?
7. Did you perceive to be in
harmony/unity with the universe?
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8. Did you have the sensation there was
a light at the end of a tunnel and/or did
you experience a more general sense of
light, or of flashing lights?
9. Were your senses more vivid? 18
10. Did you experience any extra
sensory perceptions (ESP)?
11. Did you seem to perceive what will
happen in the future?
12. Did you either feel separated from
(or have you lost awareness of) your
13. Did you seem to enter some sort of
14. Did you meet with mystical beings or
hear their voices?
15. Did you meet with deceased ones or
16. Did you reach any ‘point of no