What is death? Is it a process? A state of non-being? A continuum? In researching the science of death, I realized that there is no concrete answer; what’s more, there’s even a blurred line between life and death.
We experience death every day. At least our cells do. Take your skin: it’s estimated that roughly 40,000 skin cells complete their life cycle and are shed every hour, floating off as common house dust, completely unbeknownst to us. Cardiac cells are also actively dying, and the lining of our gut is in a dynamic state of regeneration. Cells that are injured or not working properly are programmed to commit suicide in a controlled fashion, a process known as apoptosis that was first described over 50 years ago. Necrosis, another cellular death process has traditionally been regarded as a passive and unregulated process, but just in the past few years we’ve learned that even this process is more complex than it first appears. There has even been a rise in ‘new’ cellular death subtypes in the field of biology. One of these new cell death types is a programmed necrosis, known as, necroptosis. Whatever the ultimate reason, our cells, at least, have perfected the art of dying well.
Oxygen is our ultimate life source. Within minutes of losing oxygen, the heart of a healthy person ceases to function. As the heart stops, fresh blood stops circulating oxygen to our organs and brain, and we eventually die. But this dying process is still not well understood. Because we often lose ‘consciousness’ while the heart is trying to pump, the brain has always been assumed to be under-active during cardiac arrest. But in 2013, University of Michigan researchers found that the brain emits gamma waves (the waves associated with waking consciousness) even after the heart stops beating. Moreover, in 2015, they found that during cardiac arrest, the brain synchronizes with the heart and the brain-to-heart connectivity intensifies. However, this brainstorm, likely in an effort to jolt the heart into beating, sends the heart into an accelerated demise. The researchers theorize that in controlling the brain’s electrical output during death, we may be able to rescue heart function in emergency settings someday. And that’s good news for the more than 400,000 Americans affected by sudden cardiac arrest annually.
While science continues to uncover the mysterious processes underlying death, medicine is blurring the line between life and death. Until the 1950s, once any one of the vital functions like heartbeat, electrical brain activity or respiration ceased and shut down the remaining bodily systems, you were considered dead, plain and simple. With the advent of the mechanical ventilator, which forces oxygen in and out of the lungs, a new category of death called brain death arose. In 1968, Harvard medical school reported “a new criterion for death” in their landmark paper, A Definition of Irreversible Coma. Clinicians still use the apnea test to determine clinical brain death, where a patient is briefly disconnected from a respirator to see if they can breathe on their own, and thus determine if the brain stem is functioning. If they cannot breathe, they are pronounced brain dead. Brain dead patients retain several attributes associated with life, such as skin color, warm skin, heartbeat, kidney function, etc. Organ harvesting, and even baby delivery, can take place after brain death is established. Since the body in this condition appears relatively alive, the philosophical question of someone’s ‘aliveness’ arises for many. (To clarify, brain death refers to cases of no obvious brain function, not a coma or vegetative state.). That a person is dead when all brain functions cease is a commonly accepted medical view, but there are still other viewpoints, such as defining a person dead only after their heart stops beating. As medicine and science continue to redefine death, technology is also blurring the line between life and death. A former colleague of mine and co-founder of the Brain Preservation Foundation has recently awarded a team of researchers for successfully cryopreserving (memories and all) an entire rabbit brain, marking the first time a whole mammalian brain has been kept in near-perfect condition for future use. This ‘future use’ is still up to the imagination, but futurists like Ray Kurzweil predict that uploading our brain to either a machine or a new body is no longer beyond the realm of possibility. Of course, the science here is very new, but we’ve clearly moved beyond a black and white definition of death. There is no doubt that research and medicine have redefined the science of dying. In my next post, I will explore how culture and technology are redefining the art of dying.
As medicine and science continue to redefine death, technology is also blurring the line between life and death.
Dr. Claudia Aguirre