Searching for proof of the afterlife

A large study that tracked cases of cardiac arrest to look for evidence of an afterlife was recently published in a well-respected journal called Resuscitation.

It promptly led to headlines that screamed "First hint of 'life after death' in biggest ever scientific study" in The Telegraph, for example.

On closer scrutiny, however, the study is hardly conclusive for at least three reasons: it has only one "verified" case to report; this single case itself might not be all that it is cracked up to be; and this very case was verified by a lead investigator who is not a neutral researcher but a leading activist in circles promoting the idea of the near-death experience as evidence of an afterlife.

A near-death experience is one where a clinically dead patient is revived, and who tells of feeling detached from the body while dead, floating in serenity to the ceiling, then moving upwards towards a light, or a tunnel of light, all the while feeling safe and warm. They may describe in great detail events that they "perceived" while clinically dead, which are then later corroborated by third parties.

If such near-death experiences were objectively verified, there might be a prima facie case for the hereafter.

When the heart stops during a cardiac arrest, the brain is starved of oxygen carried in the blood. Within 20 to 30 seconds, the brain ceases functioning. Hooked up to an electroencephalogram (EEG), the brain would show no electrical activity during cardiac arrest. If the heart does not resume, irreversible death within minutes is likely.

Since the brain generates the "mind", when the brain stops functioning in cardiac arrest, survivors shouldn't be able to recall any near-death experiences at all. Yet some do.

So, what might be the source of such awareness, consciousness, learning and memory while clinically dead during cardiac arrest?

The source is unlikely to be the brain's surface, which is the grey matter that generates the electrical activity that an EEG test detects. The grey matter is that which is responsible for thinking, perceiving and the human use of language. EEGs show that such activity stops in a brain-dead patient.

Maybe the source of a near-death experience lies deeper in the brain, which may be more resistant to a lack of oxygen. Such an area may continue to function in the short period of cardiac arrest in survivors who are revived quickly.

Recent advances suggest that this brain area might well be the hippocampus that lies deep inside the brain. It is responsible for memory and learning. About a year ago, researchers discovered some brain waves in people who were in an extremely deep coma, even when the EEG had flatlined.

Unknown until then, these brain waves, now called Nu-complexes, are generated in the hippocampus. But these special waves can be detected only with probes placed inside the brain's cells, unlike EEG electrodes, which are only stuck to the scalp.

Actually, a flatline EEG simply means that there is no activity in the grey matter - a thin layer of tissue measuring 1.5mm to 5mm, which covers the outermost part of the brain.

But even when the grey matter is not functioning, the hippocampus, which is located much deeper inside the brain, can apparently remain active. If it is indeed more resistant to a lack of oxygen, it may well be able to generate some sort of learning and create memories during cardiac arrest.

If that is the case, near-death experiences cannot be taken as proving there is a hereafter.

The study in question was published this month, entitled Aware - Awareness During Resuscitation - A Prospective Study. For the study, 2,060 cases of cardiac arrest across hospitals in Austria, Britain and the United States were seen over four years.

In each case, the brain oxygen level during resuscitation was measured using infrared sensors stuck to the patient's forehead.

Of the 2,060 cases, only 16 per cent were successfully resuscitated. Of these, only 101 were well enough to be fully interviewed, of whom 9 per cent reported some kind of awareness during arrest.

But of these, only two patients claimed the full near-death experience, "seeing" and "hearing" actual events during their resuscitation. Of the two, one was too ill to be interviewed again for verification. The other was verified a year later by lead investigator Sam Parnia, director of resuscitation research at Stony Brook University in New York.

The details about this second case are instructive. His near-death experience was said to have occurred during three specific minutes of arrest, because he said he heard the automated defibrillator used to shock his heart back to life announcing "shock the patient, shock the patient".

The defibrillator software could help pinpoint precisely when during the resuscitation he might have heard that.

But this is less impressive than it sounds since the use of defibrillators in resuscitation is commonly portrayed on TV and somewhat widely known. That patient, a social worker, would have been aware of, or could have learnt in the intervening year, about resuscitation procedures.

Moreover, there is every reason to be wary of Dr Parnia's claim to have verified the details. He was the co-author of a best-selling book published last year called Erasing Death, in which he revealed preliminary findings about this case - the only verified one - before the peer-reviewed paper was even published this month.

Dr Parnia is a well-known activist in the community that believes near-death experiences prove that there is an afterlife. All this suggests that he could be a biased investigator.

But even if he did conduct the verification exercise objectively and accurately, a single case is an anecdotal report, not a statistically significant finding.

Since the verification exercise was conducted a year later, there would have been ample opportunity for the patient to learn about near-death experiences from more earthly sources and later reconstruct the details of his own near-death experience.

This is not to accuse the patient of lying but memory can play tricks on us, and even create false memories for things that never happened. This is especially likely after a profoundly transformative experience like a cardiac arrest, because people want to make traumatic experiences meaningful.

While previous studies of near-death experiences have always been small, Aware was a big one.

Unfortunately, it did not offer irrefutable evidence for the afterlife. It failed to show that the mind can exist without a fully functioning brain. Thus, the question of whether there is life after death remains a mystery as much as ever.