Some people in a coma seem to be able to imagine themselves swimming or walking
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One in five coma patients may be “locked” in a dream state, meaning they are aware of their surroundings but unable to communicate. Some people with severe brain damage who are unable to move or speak can carry out complex mental tasks when given instructions, a large study has found.
“When people think this phenomenon is rare,” it’s easier to ignore it. Nicholas Schiff Weill Cornell Medical College in New York. But now, in light of the new research, “no one can ignore it.”
People with so-called disorders of consciousness are either in a coma or vegetative state, unaware of their surroundings, or in a minimally conscious state, occasionally showing signs of wakefulness, such as opening their eyes, but with minimal awareness. In 2019, researchers found that one in 10 of these patients may be trapped in consciousness.
To find out whether doctors were missing patients in this state, Schiff and his colleagues conducted eight years of behavioral and brain imaging tests on 353 people with severe brain injuries at six international centers.
Participants were asked to imagine performing a series of activities, such as playing tennis, swimming, clenching their fists or walking around their home, for 15 to 30 seconds, then pause and imagine the activities again. This process was repeated seven times over 5 minutes.
For people without impaired consciousness, these thoughts produce distinctive brain activity that can be identified through MRI scans or electroencephalograms (EEGs). Of the 353 people with brain damage, 241 had no outward response to verbal commands. But 25% of them had brain activity comparable to that of volunteers without brain damage. For those in a coma or vegetative state, the figure was 20%.
“These are very difficult tasks—try to imagine swimming on and off for five minutes,” Schiff said. “We don’t know exactly what they were going through, but the fact that they could do it means there’s a good chance they were conscious.”
Schiff said an estimated 300,000 to 400,000 people worldwide suffer from long-term disorders of consciousness, meaning as many as 100,000 people could have hidden consciousness.
This research is of great significance. RananggironEmeritus Professor of Medical Ethics at Imperial College London. He said that for many people, continuing to live while unconscious is futile at best and abhorrent at worst. “However, if the loss of consciousness is only superficial, as these studies suggest, then it is foreseeable that more people would wish to continue living and that their wishes would be sought before decisions were made to stop life-prolonging treatments.”
He said several ethical issues, including respect for people’s autonomy and human rights, “need to be reassessed in light of these studies.”
The findings also raise questions about the fairness of MRI and EEG access. Erin Paquette “If these technologies are not available to non-specialty centers, patients at these centers may not have the same opportunities as others to change the trajectory of their lives,” said researchers from Northwestern University in Illinois.
Schiff said brain-computer interfaces (BCIs) could provide a way for people with impaired consciousness to communicate in two directions, but they are not commonly used in this population. A recent study showed that Training BCI to transform brain activity takes just 30 minutes Related to trying to convert speech to text on the screen.
“Why not give them to people with impaired consciousness and see if they can use it to communicate?” Schiff said. “Worst case scenario, you could get two weeks of useful data, best case scenario, you could free them.”
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