In the Spring/Summer edition of Harvard Medicine, associate editor Molly McDonough offers an article on new findings about consciousness among the comatose. Doctors, she says, can be very surprised when patients who do not seem to respond are found to show hidden awareness. Neurologist Brian Edlow certainly was:

Edlow, now a critical care neurologist and an HMS associate professor of neurology at Massachusetts General Hospital, remembers the first time it happened. He was a medical student, and his patient, a young man, was unconscious after being hit by a car while riding a bike. The man had been unresponsive for two weeks. But that morning, Edlow grasped the patient’s hand and asked him to squeeze it — and the young man squeezed back.

“The Covert Consciousness Dilemma,”

That was back in 2006. Edlow was also hearing about Adrian Owen and colleagues’ landmark paper, published in Science, about establishing communication with a patient in a vegetative state.

Owen was using an fMRI machine, which detects local changes in blood flow in the brain that often correlate with brain activity and various mental states, to establish commuication with a woman who had been in a persistent vegetative state (PVS) for several years after a car accident:

While she was in the machine, he asked her to think about things— things like playing tennis or walking across the room. Remarkably, blood vessels in areas of her nearly destroyed brain lit up, which suggested that she might be aware of his question and thinking about it. Wanting to be sure, he did fMRI imaging on normal volunteers, asking the same questions. And they had identical fMRI responses!

To be sure that the patient was really responding and thinking, he took the test a step further. He asked her to do the same things, except that he scrambled the words so his requests no longer made sense. Her brain was silent. That implied that she genuinely understood what he had asked her the first time. So her initial response wasn’t just due to brain activation by the sound of his voice. She had understood.

Michael Egnor, “Are People in a Persistent Vegetative State Mindless? Maybe Not,” Mind Matters News, April 24, 2025

Edlow went on to do research that showed that brain injury patients who don’t respond to the usual tests, like bedside commands, often show evidence of awareness when their brains are scanned. A 2024 study of 241 adults who could not follow bedside commands also showed that about 60 (a quarter of them) “may perform cognitive tasks that are detected on functional magnetic resonance imaging (fMRI).”

More than that, of 112 of the brain injury patients who could follow bedside commands, thus demonstrating that they were conscious, 69 (over 60 percent) flunked the brain fMRI and EEG brain scans. McDonough offers, “In other words, even patients who show outward signs of consciousness can struggle to pass the tests. That suggests the tests are demanding enough to miss some conscious people — and that cognitive motor dissociation could be even more common than the reported 25 percent.”

The dilemma is, What to do next?

Life support is often shut off when it is assume that people will never regain consciousness. But it may not be so simple. And, as Edlow asks, “The question is, once you identify someone as being covertly conscious, what now?” The evidence as to whether covertly conscious people are more likely to recover tha those who show no evidence of consciousness is mixed:

Some studies have found that its presence does not predict prognosis. But research in acute settings shows more promising links. A 2019 study by researchers at Columbia University found that among patients in the ICU, 41 percent of those who showed signs of cognitive motor dissociation [covert consciousness] shortly after injury reached functional independence within a year — for example, they were able to eat, go to the bathroom, and get dressed — compared with only 10 percent of those who did not. Covert Consciousness Dilemma”

A great deal of work is needed in clinical studies to provide a large enough database to help guide treatment decisions. Edlow hopes that brain–computer interface technology like Neuralink will help researchers communicate with covertly conscious people.

McDonough also talked to neurologist Michael Young about patients who have recovered from states of covert consciousness:

Young has recently been interviewing patients who have recovered from states of covert consciousness, trying to learn about their point of view. He spoke with one man who vividly recalled experiences and conversations he’d heard at times when others did not realize that he was cognizant. Perhaps if that man’s consciousness had been detected, he would have been treated differently at the time, sparing him “memories that remain traumatic to him to this day,” Young says. “That case, even if an outlier, underscores the importance of diagnostic humility.”

It also underscores the importance of programs like Neuralink that might offer new treatment options for brain damage. It is early days yet.