Monday, June 14, 2010

Trying hard to understand NDEs

I left off in my previous post by mentioning that I would raise some of the physiological aspects occurring simultaneously with the near-death experience (NDE).

To set the stage, a review of the medical literature shows that there are no particular disease states or events predominantly associated with NDEs. Among the many clinical circumstances reported to be associated with NDEs are cardiac arrest in myocardial infarction, shock in postpartum loss of blood or in perioperative complications, anaphylactic and septic shock, electrocution, coma resulting from traumatic brain injury, intracerebral hemorrhage or cerebral infarction, attempted suicide, near-drowning or asphyxia, apnea, and serious depression.

Several retrospective analyses have been conducted which have identified a number of interesting physiological correlates of NDEs. According to a 2001 study, the physiology of an NDE in patients with cardiac arrest usually includes elevated partial O2 pressure relative to other patients with cardiac arrest.

In September 2008 it was announced that an international study conducted in 25 UK and US hospitals would examine near-death events in 1,500 patient-survivors of heart attacks. The 3-year AWARE study — a follow-up to an earlier 18-month pilot study — is being coordinated by Dr.Sam Parnia of Southampton University. The goal of the study is to determine whether individuals can have an OBE with veridical (ie, real-world) visual perceptions in the absence of a heartbeat and brain activity. (As a side note, one of the simple but quite elegant fine points of the study is the inclusion of pictures visible only from the ceiling on shelves in the hospital rooms. Thus, if a patient’s spirit truly leaves the body and ascends toward the ceiling, they may be able to describe these heretofore unseen items.)

Some researchers and commentators tend to emphasize a naturalistic, neurobiological basis for the experience, while not necessarily trying to debunk NDEs. These include Susan Blackmore (1991), Birk Engmann at the Univeristy of Leipzig, and the founding publisher of Skeptic Magazine, Michael Shermer (2010). Among the explanations invoked have been destabilized temporal lobes in the brain creating NDE-prone personalities, psychopathological symptoms secondary to severe brain malfunction resulting from the stoppage of cerebral blood circulation, and other concrete scientific explanations awaiting discovery.

In my next post, we’ll take a look at some of the data that don’t fit so neatly into the purely neurobiological “box” of explanations.

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