Some people in comas can imagine themselves swimming or walking
Kenzo Tribouillard/AFP via Getty Images
As many as one in five people in a coma may be “locked in,” meaning they are aware of their surroundings but unable to communicate, and a large study has found that some people with severe brain injuries can carry out complex intellectual tasks when instructed, despite being unable to move or speak.
It was easy to ignore the phenomenon “when it was thought of as a rare event,” says Nicholas Schiff of Weill Cornell Medicine in New York, but in light of the new research, “no one can ignore this.”
People with so-called disorders of consciousness are either in a comatose or vegetative state, unaware of their surroundings, or in a minimally conscious state, with occasional signs of wakefulness like opening their eyes. In 2019, researchers found that as many as one in 10 of these people may have disorders of consciousness.
To find out whether doctors are missing these patients, Schiff and his colleagues conducted behavioral and brain imaging tests on 353 people with severe brain injuries over an eight-year period at six international centers.
Participants were asked to think about performing different activities for 15 to 30 seconds — playing tennis, swimming, clenching their fists or walking around the house — then pause and think about the activity again, seven times over the course of five minutes.
In healthy people, these thoughts produce clear brain activity that can be seen on MRI scans and electroencephalograms (EEGs). Of the 353 people with brain damage, 241 showed no visible reaction to verbal commands, but 25% of these matched the brain activity of volunteers without brain damage; for those in a coma or vegetative state, the figure was 20%.
“This is an extremely demanding task — think about swimming intermittently for five minutes,” Schiff says. “We don’t know exactly what they’re going through, but the fact that they’re able to do this means they’re likely conscious.”
Schiff said estimates suggest there are 300,000 to 400,000 people worldwide who suffer from long-term conscious disorders, and up to 100,000 who may be subconscious.
This research is extremely important, says Lannan Gillon, professor emeritus of medical ethics at Imperial College London. For many people, the prospect of being kept alive while unconscious is at best futile and at worst abhorrent, he says. “But if unconsciousness is likely to be merely spurious, as these studies suggest, we might expect more people to want to be kept alive, and to want to be consulted about their wishes, before a decision is made to withdraw life-sustaining treatment.”
Several ethical issues, including respect for people’s autonomy and human rights, “all need to be reevaluated in light of these studies,” he says.
The results also raise questions about equity regarding access to MRIs and EEGs, says Erin Puckett of Northwestern University in Illinois: “If non-specialized centers don’t have access to these technologies, their patients may not have the same life-changing opportunities as others.”
Brain-computer interfaces (BCIs) could be a way to provide two-way communication for people with impaired consciousness, but they’re not commonly used by this group, Schiff said. Recent studies have shown that it takes just 30 minutes to train a BCI to translate brain activity associated with speech attempts into text on a screen.
“Why not give it to someone who is impaired by cognitive impairment and see if we can use it to communicate with them? At worst, we’ll get two weeks of useful data, but at best, we’ll set them free.”
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(Tag ToTranslate) Brain
