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Tuesday 27 October 2020

Out-of-body experiences

Statistics suggest ~10% of us have out-of-body experiences (OBEs) – but this number could rise now scientists know how to artificially induce them! There are three main ways they can do this: by supplying hallucinogenic drugs like LSD or ketamine; by applying strong G-forces (we realised this when pilots and astronauts reported high incidences of OBEs; the cause is attributed to blood draining out of one side of the brain: yikes!); or by extreme sensory loading: either overloading or depriving the senses (extreme sensory overload is a form of torture). In a 2002 study, a patient even experienced an OBE whilst conscious when researchers put a weak current through part of their brain (the temporoparietal junction) and was able to describe their sensations of falling and rising up to the ceiling!
Sometimes we sense things that aren't there. Via Wikipedia Commons.

Many people go through OBEs during near death experiences. These include remembering their resuscitation, and describing them from the perspective of an external observer. There are several common themes in near death OBEs: many report a sense of floating on the ceiling and looking down on themselves, a feeling of joy and peace, light, tunnels, or a sense of transformation[2]. However, although descriptions are uncannily accurate[1], and patients are sometimes able to recall conversation, none have yet passed visual “tests”.

In our quest to unravel the mystery of human consciousness, many are interested in out of body experiences, and in particular those arising from near death experience, and what happens to the human mind when we die[3]!

Many patients who claim a near death experience try to self determine their accuracy – interviewing medical staff to check they correctly remember the scene. However, there is a problem with this approach – when we recall a memory, we change it. As patients obtain more details about what really happened, they might (completely unintentionally) project those details into their memories, changing them[1]. This is especially true for patients who want their experience to affirm a pre-existing belief in the supernatural. So we can’t trust these self determined accounts: somebody else has to investigate them using “tests”.

Indeed, 60% of people who go through cardiac arrest are drastically changed by it – but this is not for the better: near death experiences mess with people’s sense of identity, and are associated with elevated incidences of PTSD, anxiety and depression (50%), with only 10% reporting positive impacts[2]. This may be because the temporoparietal junction is involved – the part of the brain that uses sensory information to distinguish between what is and what is not ourselves.

Needless to say, it would be horrifically unethical to induce near-death OBEs in order to do research on them.

So we still don’t know.

They didn't know about the pictures. Flaviz Guerra via Flickr.

The main theory to explain OBEs is that they occur when the brain is starved of oxygen. This theory is supported by oxygen levels monitoring, which has shown higher (low) levels in patients who undergo near death experiences during cardiac arrest than those who don’t[4].

However, there are at least 19 other theories[1], and scientists are unable to say for sure why OBEs happen or link them to particular brain activities.

Those “visual tests” mentioned earlier? They were gathered in a 2014 study called the AWAREness study[5], which started off with 2,000 people who suffered cardiac arrest over several years in several hospitals. The researchers placed pictures on shelves only visible from the ceiling and asked patients if they could recall them. Of 140 near death participants, 9 had near death experiences, and of these only 2 people claimed to have had floating-on-the-ceiling-out-of-body-experiences. They didn’t know about the pictures.

They are clearly not a statistically significant sample.

These are even worst odds that other literature, which reckons 17% of those who nearly die have a near death experience, and ~45% those report OBEs[1].

This highlights a very real problem with conducting this kind of research – unless we can induce OBEs, it’s just too hard to find enough at the right time and set up test conditions.

So, at the moment, we don’t know if our 2 participants didn’t notice the picture because they were preoccupied with watching their own death, or couldn’t – because they didn’t really leave their bodies, and their brain was doing something funky we are yet to discover...

The quest continues.

why don't all references have links?

[1] Long, Jeffrey. Near-Death Experiences Evidence for Their Reality. Missouri medicine 111.5 (2014): 372.
[2] Parnia, Sam, et al. Awareness and Cognitive Activity During Cardiac Arrest. Circulation 140.Suppl_2 (2019): A387-A387.
[3] Parnia, Sam, and Peter Fenwick. Near death experiences in cardiac arrest: visions of a dying brain or visions of a new science of consciousness. Resuscitation 52.1 (2002): 5-11. doi: 10.1016/S0300-9572(01)00469-5.
[4] Parnia, Sam, et al. A qualitative and quantitative study of the incidence, features and aetiology of near death experiences in cardiac arrest survivors. Resuscitation 48.2 (2001): 149-156. doi: 10.1016/S0300-9572(00)00328-2.
[5] Parnia, Sam, et al. AWARE—AWAreness during REsuscitation—A prospective study. Resuscitation 85.12 (2014): 1799-1805. doi: 10.1016/j.resuscitation.2014.09.004.

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