Researchers from the University of Liège (Belgium) teamed up with researchers from IANDS France and IANDS Flanders to compare near-death experiences (NDEs) occurring in coma versus non-life-threatening events. IANDS provided conceptual input and helped locate NDErs to participate. The study, reported recently in the press (also here), compared 140 NDEs from people who were in coma against 50 NDEs from people who were in non-life-threatening situations (sleep, fainting, meditation, drug or alcohol use, etc.).
The researchers scored the NDEs on the Greyson NDE scale (7 or higher out of 32 is considered an NDE) and compared the two groups by "content" (the NDE features) and "intensity" (total NDE scale score). Surprisingly, the results showed no difference in the intensity and content between the non-life-threatening NDEs and the coma NDEs. Furthermore, there was no difference in the coma NDEs depending on the cause of the coma (e.g., cardiac arrest vs. trauma vs. illness). More...
Comparing Near-Death Experiences during Coma with Those from Non-life-threatening Events
Researchers from the University of Liège, led by Vanessa Charland-Verville and Steven Laureys* with assistance from IANDS France and IANDS Flanders, published a report in the peer-reviewed journal Frontiers in Human Neuroscience. Their study compared 190 NDE reports that result from either life-threatening events leading to coma of different etiologies (called "real NDEs", n=140) or "NDE-like experiences" occurring after non-life-threatening events (n=50), such as during sleep (n=13), fainting (n=11), meditation (n=5), drug or alcohol use (n=3), or other non-life-threatening situations (n=18).
The subjects were selected based on the Greyson NDE scale (7 or higher of 32). The "intensity" of the experience was based on the NDE score (7 to 32). The "content" of the NDE was determined by the NDE scale features or elements that were present.
Surprisingly the results showed no significant difference in the intensity and content of the NDE between the “NDE-like” and “real NDE” groups. Furthermore, there was no difference in the "real NDE" (coma) group depending on the cause of the coma—anoxic condition resulting from cardiac arrest or drowning (n=45) vs. traumatic injury (n=30) vs. other cause of coma such as illness or surgical complications (n=65).
This means that neither the apparent "closeness to death" nor the specific physiological or psychological factors that were present influenced the content or intensity of the NDE. A person, for example, who has an "NDE-like" experience during sleep or meditation will tend to have the same elements (e.g., feelings of peace, separation from the body, a brilliant light) and the same intensity (total NDE score: mean of 16 for "real NDEs" and 17 for "NDE-like") as a person actually near death, for example, who has a so-called "real NDE" while suffering anoxia and coma from a cardiac arrest.
NDEs occurring on either end of the "closeness to death" spectrum cannot be distinguished—they are the same experience. Furthermore, there was no significant difference in the content and intensity of the NDE depending on the etiology of the acute brain insult resulting in coma (anoxia vs. trauma vs. illness or surgical complications).
These results imply that there is no physiological explanation that can account for NDEs. Given that the "NDE-like" experiences occurred in non-life-threatening situations such as sleep and meditation, the explanation that NDEs are triggered by the strong belief or fear of dying also does not hold.
Differences Retrospectively versus Prospectively?
In order to check whether the present study results were skewed because of retrospective recruitment of self-reported NDEs that occurred several decades prior to enrollment in the study, the researchers compared their anoxic coma group (n=45) with three prospective studies of cardiac arrest NDEs (combined n=42).
There was no significant difference in the intensity of the NDEs (mean NDE score of 15 retrospectively vs. 13 prospectively). Four of the sixteen NDE features (i.e., altered time perception, enhanced understanding, heightened senses and sense of harmony/unity with the universe) were reported significantly more retrospectively. However, an encounter with deceased or religious spirits was reported significantly more prospectively. These differences may be due to embellishment of memories over time in the retrospective cases, but they also may be due in the prospective cases to (1) the lack of integration of the experience, (2) the reluctance of the subject to disclose details in the first week after the experience, and (3) transient episodic amnesia due to the anoxic brain insult.
The researchers concluded: "It seems that NDEs cannot be explained solely by the closeness to death or by the etiology of the precipitating factor. The question whether the NDEs' extraordinary features can be fully explained by cerebral activity is still a matter of debate..."
The results of this study strongly suggest that an NDE is a phenomenon that occurs completely independently of the NDEr's physiological condition, the circumstances of the event or the "trigger" of the experience. Therefore, there is no single physiological or psychological explanation for NDEs – an NDE is a state of consciousness that can be triggered by many different types of events and conditions but is not caused by any specific physiological or psychological condition.
And that certainly implies that the commonality of the near-death experience has to do with the common state of consciousness that occurs during NDEs—the sense of separation from the body; the vividness of the experience and the indelible memories of it, frequently despite severe physiological dysfunction; the loss of the fear of death; and so on. There must be a common factor or common cause that is independent of physiology, for example, that, according to one theory, under various triggers or conditions, consciousness as an entity can separate from and operate independent of the physical body.
Apparent Contradiction with Earlier Study
Charland-Verville and colleagues did not address the apparent contradiction between their results and the oft-cited analysis by Owens, Cook and Stevenson (1990). In that study, NDErs whose records confirmed had been medically so close to death that they would have died without medical intervention (n=28) reported significantly more enhanced perception of light and enhanced cognitive powers, than did NDErs whose records showed they were not in danger of dying, even though most of them thought they were (n=30).
There are three major differences between the two studies: (1) the 1990 study did not use the Greyson NDE scale and compared elements that are not included in that scale (e.g., experience of a tunnel), (2) the 1990 study compared two groups of NDE reports using different criteria, not specifically selecting the medical extremes of coma and non-life-threatening situations, and (3) the 1990 study combined several NDE elements as a generic "enhanced cognitive function" (e.g., speed, logic and clarity of thoughts, control of cognition, and overall clarity and vividness of senses).
These study differences probably do not explain the difference in the final result, that is, whether NDEs depend on specific physiological or psychological factors. Based on the results of the present study, there should be no difference between samples of NDE reports chosen by any physiological or psychological criteria. But indeed, there are notable differences in the specific results of the two studies: in the 1990 study, only 40% (12 of 30) NDErs not near death reported enhanced light, compared with 84% (42 of 50) "NDE-like" NDErs in the present study; in the 1990 study, 50% (13 of 26) of NDErs not near death reported enhanced cognitive function, compared with at least 68% (34 of 50) of "NDE-like" NDErs in the present study.**
These differences are probably due to inadequate statistical sampling in one or both studies or possibly incomplete NDE narratives in the 1990 study because a standardized instrument was not used in all cases. In any case, a replication of the present study is warranted.
Robert Mays, NDE researcher
- Charland-Verville, V., Jourdan, J.-P., Thonnard, M., Ledoux, D., Donneau, A.-F., Quertemont, E., and Laureys, S. (2014). Near-death experiences in non-life-threatening events and coma of different etiologies. Frontiers in Human Neuroscience, 8(203). doi:10.3389/fnhum.2014.00203.
- Owens, J. E., Cook, E. W., and Stevenson, I. (1990). Features of "near-death experience" in relation to whether or not patients were near death. The Lancet, 336:1175-1177.
* Dr. Laureys is Clinical Professor at the University of Liège (Belgium) and Research Director at the Belgian National Fund of Scientific Research. He is also the principal author of another paper that was commented on last year in the IANDS news, about the quality of memory of NDEs compared with other memories.
** Because the 1990 study combined several criteria for "enhanced cognitive function", there is no easy comparison between the studies without the specific data. It is very likely that more than 68% of the 50 "NDE-like" subjects in the present study would be judged to have experienced "enhanced cognitive function" when all of the relevant Greyson elements are combined. The 68% represents only reports of "more vivid senses".