Many people in a coma seem to think about complex tasks when instructed, which suggests they are aware of what is going on around them
By Helen Thomson
14 August 2024
Some people in a coma seem to be able to imagine themselves swimming or walking
KENZO TRIBOUILLARD/AFP via Getty Images
One in five people in a coma may be “locked in”, meaning they are aware of their surroundings but unable to communicate. A large study has found that some people with severe brain damage can carry out complex mental tasks when instructed, despite not being able to move or speak.
It was easier to discount the phenomenon “when it was thought to be a rare occurrence”, says Nicholas Schiff at Weill Cornell Medical College in New York. But now, given the latest study, “no one can ignore it”.
People with so-called disorders of consciousness are either in a coma or a vegetative state, where they show no awareness of their environment, or a minimally conscious state, where they show occasional signs of arousal, such as opening their eyes, but minimal awareness. In 2019, researchers discovered that 1 in 10 of these individuals may be locked in.
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To find out if doctors were missing people in this state, Schiff and his colleagues carried out behavioural and brain imaging tests on 353 people with severe brain damage over eight years at six international centres.
The participants were asked to think about performing a range of activities – such as playing tennis, swimming, clenching their fist or walking around their home – for 15 to 30 seconds, before pausing, and thinking about the activity again. This was repeated seven times over 5 minutes.