A patient in a seemingly vegetative state, unable to move or speak, showed signs of attentive awareness that had not been detected before, a new study reveals. This patient could focus on words signaled by the experimenters as auditory targets as successfully as healthy individuals. If this ability can be developed consistently in certain patients who are vegetative, it could open the door to specialized devices in the future and enable them to interact with the outside world.
The research, by scientists at the Medical Research Council Cognition and Brain Sciences Unit and the University of Cambridge, was published last week in the journal Neuroimage: Clinical.
For the study, the researchers used electroencephalography, which noninvasively measures the electrical activity over the scalp, to test 21 patients diagnosed as vegetative or minimally conscious and eight healthy volunteers. Participants heard a series of different words - one word a second over 90 seconds at a time - while being asked to alternatingly attend to either the word "yes" or the word "no," each of which appeared 15 percent of the time. (Some examples of the words used include "moss," "moth," "worm" and "toad.") This was repeated several times over a period of 30 minutes to detect whether the patients were able to attend to the correct target word.
The researchers found that one of the vegetative patients was able to filter out unimportant information and home in on relevant words they were being asked to pay attention to. Using fMRI brain imaging, the scientists also discovered that this patient could follow simple commands to imagine playing tennis. They also found that three other minimally conscious patients reacted to novel but irrelevant words but were unable to selectively pay attention to the target word.
These findings suggest that some patients in a vegetative or minimally conscious state might in fact be able to direct attention to the sounds in the world around them.
Srivas Chennu, a research associate at the University of Cambridge's department of clinical neurosciences, said: "Not only did we find the patient had the ability to pay attention, we also found independent evidence of their ability to follow commands - information which could enable the development of future technology to help patients in a vegetative state communicate with the outside world."
Seniors who don't sleep well are more likely to have high levels of beta-amyloid, a biomarker for Alzheimer's, in their brains. Previous studies had linked disturbed sleep to cognitive impairment in older people. The new findings, published in JAMA Neurology, suggest that sleep problems may contribute to its development.
Alzheimer's disease is a progressive, irreversible brain disease that slowly destroys memory and thinking skills. According to the National Institutes of Health, as many as 5.1 million Americans may have the disease, with first symptoms appearing after age 60.
Brains of Alzheimer's patients have high levels of amyloid plaque, deposits of a substance consisting largely of beta-amyloid. According to the National Institute on Aging, it is not yet known whether amyloid plaque causes the disease or is a byproduct of it.
In a cross-sectional study of adults with an average age of 76, a team led by Adam Spira of the Johns Hopkins Bloomberg School of Public Health examined sleep as reported by research participants. Their duration of sleep ranged from more than seven hours a night to no more than five hours. Beta-amyloid in their brains was measured by positron emission tomography, or PET scans.
The results: Shorter sleep duration and lower sleep quality were both associated with greater beta-amyloid buildup.
Spira says that his study doesn't prove a causal link between poor sleep and Alzheimer's disease. Longitudinal studies with objective sleep measures are needed to further examine whether poor sleep actually can contribute to or accelerate Alzheimer's disease, he says.
"These findings are important in part because sleep disturbances can be treated in older people," Spira says. "To the degree that poor sleep promotes the development of Alzheimer's disease, treatments for poor sleep or efforts to maintain healthy sleep patterns may help prevent or slow the progression of Alzheimer's disease."