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Researchers studying people in vegetative states make shock discovery that could redefine consciousness
Unresponsive patients may still be conscious enough to 'perform cognitive tests,' a major international study suggests.
Researchers in the US, UK and Europe performed MRIs and other brain scans on over 200 people with severe brain injuries that left them in a coma or vegetative state.
The team asked them to imagine various scenarios like 'opening and closing your hand' to measure brain activity and responses.
They found that one in four participants were about to repeatedly follow this instruction, suggesting that patients who are largely unaware of what's happening around them may actually be able to understand language, pay attention, and perform simple tasks.
The researchers said the findings raise ethical concerns about taking patients off life support or removing their organs too early.
Researchers in four countries found that one in four patients deemed 'unresponsive' were able to follow basic instructions, based on brain scans
The researchers said the findings could prevent patients being removed from life support too early when they still have signs of awareness
Dr Yelena Bodien, lead study author and investigator from Massachusetts General Hospital, said: 'Some patients with severe brain injury do not appear to be processing their external world.
'However, when they are assessed with advanced techniques such as task-based fMRI and EEG, we can detect brain activity that suggests otherwise.
'These results bring up critical ethical, clinical, and scientific questions – such as how can we harness that unseen cognitive capacity to establish a system of communication and promote further recovery?'
The study, published Wednesday in the New England Journal of Medicine, included 241 participants from six different sites in the US, UK, Belgium, and France.
All of these patients were adults who had suffered some form of brain injury, resulting in a coma, vegetative state, or minimally conscious state - where a person has generally limited signs of awareness and responses to stimulation.
The majority suffered undefined 'brain trauma' - traumatic brain injuries, for example - followed by cardiac arrest and stroke.
Patients were 38 years old on average when they were injured, and 64 percent were male.
All participants underwent electroencephalograms (EEGs) and MRI scans to measure electrical activity and overall brain function. Data was collected over 17 years.
Based on these scans, the team found that 25 percent of participants were able to respond to instructions like 'imagine opening and closing your hand,' followed by 'stop imagining opening and closing your hand.'
This is up to 10 percent more than older estimates, suggesting that more patients could have remnants of consciousness than previously thought.
The phenomenon is called cognitive motor dissociation (CMD), which occurs when patients seem unresponsive but still have brain activity, such as remembering.
Actress Mamie Laverock went on life support for several weeks after surviving a fall from a five-story building. Despite the unlikely odds, she survived and took her first steps (right) after being removed from life support
Four-year-old Maisie was taken off life support in March, just two days after she was admitted to the hospital with flu-like symptoms. It's unclear if she had any awareness or if keeping her on support for longer could have improved her odds of survival
The experts noted that these findings could help redefine consciousness and prevent patients from being taken off life support or having their organs taken from them when they have a chance to improve.
Several patients have benefitted from being kept on support for longer periods of time. Hallmark actress Mamie Laverock, for example, was placed on life support in May after she fell off a fifth story balcony.
She remained on life support for several weeks, eventually waking up. Three months after the injury, she took her first steps.
Other patients were taken off quickly, making it difficult to know if staying on support would have allowed them to eventually pull through. One gripping case was that of four-year-old Maisie, an Ohio toddler who came down with flu-like symptoms in March.
The preschooler suffered a stroke and severe brain swelling, leading her to be removed from life support just two days after arriving at the hospital.
'Failing to detect cognitive motor dissociation can have serious consequences, including premature withdrawal of life support, missed signs of awareness, and lack of access to intensive rehabilitation,' Dr Bodien said.
Additionally, the findings could encourage doctors to pay more attention to subtle signs of awareness in their patients or give them enrichment, such as playing music or talking to them, that could speed up their recovery.
Dr Nicholas Schiff, senior study author and neuroscientist at Weill Cornell Medicine in New York City, said: 'We find that this kind of sharp dissociation of retained cognitive capabilities and no behavioral evidence of them is not uncommon.
'I think we now have an ethical obligation to engage with these patients, to try to help them connect to the world.'
However, the study had several limitations, with the main one being that each institution followed different procedures for testing patients, which could have skewed the data.
The study also used a small sample size.
The team plans to conduct additional research to fully explore how conscious patients in thee states may be.
'We know that cognitive motor dissociation is not uncommon, but resources and infrastructure are required to optimize detection of this condition and provide adequate support to patients and their families,' Dr Bodien said.