Mind Matters Natural and Artificial Intelligence News and Analysis
senior in coma.jpg
side view of senior man in coma on bed in hospital

Researchers: Comatose People Can Have “Covert Consciousness”

Claassen and Edlow found that the brain patterns of a woman who could not respond physically to commands showed that she recognized them

Columbia University neurologist Jan Claassen and Harvard medical school neurologist Brian L. Edlow introduce us to a vital new concept in consciousness: “covert consciousness,” which is experienced by 15–20% of people who are in a coma: Thirty-year-old New York City resident Maria Murkevich, for example, suffered a ruptured blood vessel in her brain and was comatose. Conventional tests (wiggle your toes, etc.) produced no response but her loved ones still believed she was “in there.”:

They were right. But it took a high-tech method to demonstrate that:

The medical team gave her an EEG — placing sensors on her head to monitor her brain’s electrical activity — while they asked her to “keep opening and closing your right hand.” Then they asked her to “stop opening and closing your right hand.” Even though her hands themselves didn’t move, her brain’s activity patterns differed between the two commands. These brain reactions clearly indicated that she was aware of the requests and that those requests were different.

Jan Claassen, Brian L. Edlow, “Some People Who Appear to Be in a Coma May Actually Be Conscious” at Scientific American (November 1, 2022 print edition date) The paper is open access.

Over a year, Murkevich slowly recovered and she now works as a pharmacist.

The “covert consciousness” she demonstrated is, the authors say, changing our understanding of disorders of consciousness. Significantly, patients who demonstrate covert consciousness — if detected early — are more likely, according the authors’ study and others, to return to normal consciousness and “functional recovery.” Some neurologists are now focusing on identifying covertly conscious patients so as to direct needed help their way:

Building on the momentum of these studies, scientists came together in 2019 to launch the Curing Coma Campaign, an international collaboration led by the Neurocritical Care Society to direct medical resources and public attention to the condition, with the goal of developing new therapies that promote recovery of consciousness.”

Jan Claassen, Brian L. Edlow, “Some People Who Appear to Be in a Coma May Actually Be Conscious” at Scientific American (November 1, 2022 print edition date) The paper is open access.

They see as an “ethical imperative” that protocols and tools for detecting covert consciousness are available at the bedside so that patients who are conscious but can’t demonstrate it physically can be identified.

One curious fact that Klaassen and Edlow relate is that people don’t remember covert consciousness: “Mazurkevich, for instance, does not recall any aspect of her time in the intensive care unit when she appeared to be comatose. So the experience is still largely a mystery.”

Some other things we have learned about comas:

Can loved ones in a coma hear us? Adrian Owen showed, using MRI, that a deeply comatose patient could hear and understand. Michael Egnor notes, “His research has been repeated by a number of other laboratories on many, many patients with persistent vegetative state. And about forty percent of people in persistent vegetative state show high levels of intellectual functioning even in deep coma.” So it’s wise to assume they can.

Can people in comas have abstract thoughts? It’s hard to tell because we need to distinguish between concrete thought (a chocolate sundae!!) And abstract thought (“but the 2,000 calories… ”). For sure, many can think. But not much testing has been done about the exact nature of the thoughts. Neurologists have necessarily focused on more basic, recovery-related issues.

Further evidence that some comatose people really do understand: “The researchers from Columbia University and New York University conducted a prospective study involving 104 patients with acute brain injury. The patients were in a deep coma with no motor response to verbal commands. They gave alternating commands to the patients and used machine learning analysis of each patient’s brain waves during these commands. They found that cognitive responses to verbal commands could be detected in some patients using analysis of the brain waves. Fifteen percent of the completely unresponsive patients had brain activation on EEG that correlated with these verbal commands, despite having no physical motion in response… Patients who showed evidence for brain activation were twice as likely to recover to the point of physically following verbal commands in the future as compared with patients who showed no brain activation. On longer follow-up, patients with brain activation in a deep coma were three times as likely to be able to carry out independent activities of life as compared with patients with no activation.” – neurosurgeon Michael Egnor, 2019

Can brain death be reversed? Among the recently diagnosed brain-dead, it may be possible: “As most leaders in this field acknowledge that residual “nests” of neuronal activity and residual blood flow do indeed exist in the recently diagnosed brain-dead, it makes sense that such revivals are theoretically possible with the right neuro-regeneration and remodeling tools. Additionally, it is widely acknowledged that supported brain-dead subjects can continue to maintain their own circulation, digestion, metabolism, excretion, hormonal balance, growth, sexual maturation, fetus gestation, wound healing, and spike a fever.” It’s hard to be definitive about anything as complex as the human brain. We only learned in recent years that some comatose people are covertly conscious.

Note: Incidentally, Klaassen and Edlow dispel the myth that people suddenly “awaken” from comas, as we sometimes see in books, plays, and movies. If they start to come round, they typically require weeks or months of rehabilitation before regaining more independence.


You may also wish to read: Four researchers whose work sheds light on the reality of the mind. The brain can be cut in half, but the intellect and will cannot, says Mike Egnor. The intellect and will are metaphysically simple. A good deal of research on the reality of the mind has been done but it has not always received much attention


Mind Matters News

Breaking and noteworthy news from the exciting world of natural and artificial intelligence at MindMatters.ai.

Researchers: Comatose People Can Have “Covert Consciousness”