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Certain people who are in vegetative or minimally-conscious states may be capable of paying attention and answering simple questions with their minds, suggests a new Canadian study of three people.
Using specialised MRI machines, researchers found the brains of patients who were physically non-responsive lit up on cue when the patients were told to answer yes or no questions or pay attention to specific words.
"The questions that we posed to ourselves were whether patients who are completely non-responsive... have the ability to pay attention and whether we can use this as a way to communicate with them," Lorina Naci, the study's lead author from Western University in London, Ontario, told Reuters Health.
Previous research found that some people with no outward signs of consciousness after severe brain injuries can increase their brain activity when prompted.
Less was known, however, about whether those patients could focus on specific commands and maintain that focus for prolonged periods of time.
The study
For the new study, Naci and her colleague Adrian Owen looked at three patients who suffered severe brain injuries and were left in minimally-conscious or vegetative states.
The patients were put through a functional magnetic resonance imaging scan that measures the amount of blood flow in certain parts of the brain, which is used as a measurement of brain activity.
After making sure the patients could hear, the researchers tested whether they could follow commands by playing a series of sounds and telling patients to pay attention or not pay attention.
More activity
They then compared the patients' brain scans to see whether there were differences on the images. Overall, the patients' scans showed more activity following the orders to pay attention.
What's more, two of the patients who completed additional testing were able to pick specific words in a series to recognise. Their scans showed more activity when those words were said.
They could also respond to basic yes or no
questions about themselves and their surroundings.
Patients would be asked a yes or no question and their brain scan would light up when the researchers said the correct answer.
For example, they could respond no to the question, "Are you in a supermarket?" and yes to, "Are you in a hospital?"
"We scanned the patient in two scanning visits five months apart and we found that the patients activated the same brain regions," Naci said."We are 99% confident in the results... we can deduce that it is significant and driven by the patient," she said.
"I think the upshot of this is that there is enough data now to know that patients are being misidentified as unconscious when they have levels of consciousness," Dr Nicholas Schiff, a neurologist at Weill Cornell Medical College in New York, who wasn't involved in the new research, told Reuters Health.
Mentally aware
Dr James Bernat, who studies brain death at the Geisel School of Medicine at Dartmouth in Lebanon, New Hampshire, said the new study brings to light several points, including the need for new tests to diagnose patients' levels of consciousness.
"We used to think prior to seven years ago that a properly performed neurologic examination (not including functional MRI)... would be the optimal way to demonstrate whether or not a patient had awareness," Bernat, who wrote an editorial accompanying the new study in JAMA Neurology, told Reuters Health.
Studies are needed to find out how many people diagnosed as minimally-conscious or vegetative may actually be mentally aware, according to Naci.
She added that her team is currently working to develop portable brain-scanning devices and collaborating with philosophers and doctors to decide whether these minimally-conscious people can participate in their own care and make decisions." The hope for these patients is to take back some sense of their autonomy of their own fates," she said.
