People in Comas May Actually Hear What You Say

Key Takeaways

• In a recent study, one-quarter of people who were in a coma showed significant brain activity when asked to imagine playing tennis or moving their hands.
• They exhibited brain activity in the same regions as people given the same commands who did not have brain injuries.
• The findings present significant questions for loved ones considering end-of-life decisions for people in comas or persistent vegetative states.

About 1 in 4 people with severe brain injuries who appear unresponsive to commands and unaware of what's going on around them may in fact be conscious and have the same brain activity seen in healthy people, a condition called cognitive-motor dissociation, according to a new study.

Although participants in the study could not show an external physical response (such as a thumbs-up) when asked, they repeatedly showed brain activity when asked to think about two specific activities - opening and closing their hand or playing tennis.

The finding that 25 percent of people unresponsive to verbal communication retain a high level of cognitive function should change how healthcare providers interact with these patients, says the corresponding author Nicholas Schiff, MD , a professor of neurology and neuroscience at Weill Cornell Medicine and a neurologist at NewYork-Presbyterian Weill Cornell Medical Center, both in New York City.

"I think we now have an ethical obligation to engage with these patients, to try to help them connect to the world," Dr. Schiff said in a press release.

This is a landmark study of people with these types of consciousness disorders, says Daniel Kondziella, MD, PhD , a neurologist at Rigshospitalet at Copenhagen University Hospital and the lead author of the European Academy of Neurology guideline on the diagnosis of coma and disorders of consciousness.

The overall rate of people who exhibited these signs of consciousness and brain activity is even higher than previously thought, which underscores the importance of using available tools to evaluate brain-injured patients, says Dr. Kondziella, who was not involved in the research.

1 in 4 People Unable to Visibly React to Speech May Be Able to Mentally Respond

The study began with researchers examining 353 adults with brain injury, usually caused by severe trauma or interrupted oxygen supply to the brain following strokes or heart attacks , from six different hospitals across the United States. Most participants were under care at home or in long-term care facilities, and the median time from injury was about eight months.

To find out if people could respond to commands, investigators repeatedly asked each patient to perform a series of motor tasks (for example, "keep wiggling your toes") as well as motor-related cognitive tasks, such as imagining wiggling their toes.

They found that although some people could respond, 241 people were unable to react visibly to these prompts.

All participants then underwent one or both of two types of brain scans, a fMRI (functional magnetic resonance imaging) which measures brain activity by monitoring oxygen delivered to the brain cells, or electroencephalography, which uses an electrode-covered cap that's placed on the scalp to measure brain-wave activity.

During the scan, people were told over and over for 15 to 30 seconds to imagine themselves playing tennis or opening and closing their hand. After a pause, this exercise was repeated for a total of six to eight rounds.

Researchers found that among the 241 patients in a coma or vegetative state who could not make visible responses to bedside commands, one-fourth had sustained and relevant cognitive responses - in the same brain regions that become activated in undamaged brains.

A higher percentage (38 percent) of the 112 patients who were able to physically respond to the spoken commands also showed this response. Although it might be expected that that percentage should be even higher, authors suspect that it could be because the experiment set a very high bar for what constituted consistent brain activity.

Although the study wasn't designed to identify factors that make response more likely, patients who showed brain activity tended to be younger, have injuries from physical trauma, and be living with their brain injury for longer, says Schiff.

The researchers acknowledge that there are a few limitations to the study. Not all the medical centers followed the exact same protocol, in terms of how many times the tasks were repeated during a session and the number of electrodes used in the EEG sessions.

Findings May Improve Treatment and Outcomes for People in Comas

In the United States, it's estimated that between 5,000 and 42,000 people are in a chronic vegetative state, and that between 112,000 to 280,000 individuals are in a minimally conscious state.

The fact that one quarter of the unresponsive people with cognitive-motor dissociation may be aware and capable of cognition brings up critical ethical, clinical, and scientific questions, according to the study authors.

For starters, new systems of communication for these patients, such as brain-computer interfaces, could improve their quality of life and boost their chances of recovery, says Schiff.

Unfortunately, the technology required to detect these levels of consciousness is highly complex, and at this point, only a handful of centers around the world would be able to adopt these methods, says Kondziella.

But researchers are currently studying simpler methods that have great potential to be implemented on a broader scale, he says.

Future research will explore better means of detecting cognitive-motor dissociation, since prior studies suggest that patients with this condition may have a greater chance of recovery than those who cannot perform cognitive tasks, says Schiff.

"Just knowing that a patient has this ability to respond cognitively can be a game changer in terms of life-support decisions and the degree of engagement of caregivers and family members," Schiff says.

Editorial Sources and Fact-Checking

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Sources

1. Bodien YG et al. Cognitive Motor Dissociation in Disorders of Consciousness. New England Journal of Medicine . August 14, 2024.
2. Large Study Confirms Significant Frequency of Undetected Responsiveness in Severe Brain Injury. Weill Cornell Medicine . August 14, 2024.
3. Giacino JT et al. Comprehensive Systematic Review Update Summary: Disorders of Consciousness. Neurology . September 4, 2018.

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Becky Upham

Author

Becky Upham has been professionally involved in health and wellness for almost 20 years. She's been a race director, a recruiter for Team in Training for the Leukemia & Lymphoma Society, a salesperson for a major pharmaceutical company, a blogger for Moogfest, a communications manager for Mission Health, a fitness instructor, and a health coach.

She majored in English at the University of North Carolina and has a master's in English writing from Hollins University.

Upham enjoys teaching cycling classes, running, reading fiction, and making playlists.

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