Launched in 2008, the large-scale study included 2,060 patients from hospitals in the UK, USA and Austria. Known as AWARE (AWAreness during REsuscitation), the study looked at reported experiences in relation to clinical brain-death -- or more specifically, recall of memories apparently experienced while patients were experiencing cardiac arrest.
The results, which were published this week in the refereed journal Resuscitation, links reported memories of visual awareness based on so-called out-of-body (OBE) experiences that showed a strong correlation with actual events.
The study also sought to test the validity of conscious experience using objective markets, to try to determine if reported memories were linked to real events or merely hallucinations.
Dr Sam Parnia, Assistant Professor of Critical Care Medicine and Director of Resuscitation Research at The State University of New York at Stony Brook, USA, and the study's lead author, explained: "Contrary to perception, death is not a specific moment but a potentially reversible process that occurs after any severe illness or accident causes the heart, lungs and brain to cease functioning."
"If attempts are made to reverse this process, it is referred to as 'cardiac arrest'; however, if these attempts do not succeed it is called 'death'. In this study we wanted to go beyond the emotionally charged yet poorly defined term of NDEs to explore objectively what happens when we die."
One case was validated and timed using auditory stimuli during cardiac arrest. Dr Parnia concluded: "This is significant, since it has often been assumed that experiences in relation to death are likely hallucinations or illusions, occurring either before the heart stops or after the heart has been successfully restarted, but not an experience corresponding with 'real' events when the heart isn't beating.
In this case, consciousness and awareness appeared to occur during a three-minute period when there was no heartbeat. This is paradoxical, since the brain typically ceases functioning within 20-30 seconds of the heart stopping and doesn't resume again until the heart has been restarted. Furthermore, the detailed recollections of visual awareness in this case were consistent with verified events.
Thirty-nine per cent of patients who survived cardiac arrest and were able to undergo structured interviews described a perception of awareness, but interestingly did not have any explicit recall of events.
"This suggests more people may have mental activity initially but then lose their memories after recovery, either due to the effects of brain injury or sedative drugs on memory recall," explained Dr Parnia, who was an Honorary Research Fellow at the University of Southampton when he started the AWARE study.
In the study, a 57-year-old social worker was able to recount the actions of the medical staff while he was clinically dead for three minutes. During the period, the man recalls watching doctors attempting to restart his heart from the corner of the room. He also heard two "bleeps" from a machine in the operating room at three minute intervals.
Among those who reported a perception of awareness and completed further interviews, 46 per cent experienced a broad range of mental recollections in relation to death that were not compatible with the commonly used term of Near-Death Experiences (NDEs). These included fearful and persecutory experiences. Only 9 percent had experiences compatible with NDEs and 2 per cent exhibited full awareness compatible with OBEs with explicit recall of 'seeing' and 'hearing' events.
"Thus, while it was not possible to absolutely prove the reality or meaning of patients' experiences and claims of awareness, (due to the very low incidence--2 percent--of explicit recall of visual awareness or so called OBEs), it was impossible to disclaim them either and more work is needed in this area. Clearly, the recalled experience surrounding death now merits further genuine investigation without prejudice."
Further studies are also needed to explore whether awareness (explicit or implicit) may lead to long term adverse psychological outcomes including post-traumatic stress disorder.
Dr Jerry Nolan, Editor-in-Chief of Resuscitation, stated: "The AWARE study researchers are to be congratulated on the completion of a fascinating study that will open the door to more extensive research into what happens when we die."
An alternative view suggests that the whole study was a bust, as it attempted to use hidden images which could then be "seen" by people in an OBE state, but failed to mention this in its results.