Walking speed may indicate severity of MS . . . Doctors may be able to determine the progression and severity of multiple sclerosis in a patient by measuring the time it takes them to walk 25 feet. This is according to a study published in the journal Neurology. MS is a chronic disease of the central nervous system. According to the National Multiple Sclerosis Society, around 2.3 million people worldwide suffer from the disease. Common symptoms of MS include fatigue, numbness, walking and coordination problems, vision problems and cognitive dysfunction. The "25-foot walk performance" is already used to determine the level of disability in a person suffering from multiple sclerosis (MS), but the researchers say the findings show that the time it takes for a patient to walk this distance may be an indicator of disease progression and severity. For the study, the researchers analyzed 159 patients with MS who were asked to carry out a timed 25-foot walking test. Patients were also asked about their employment, their ability to do daily activities, and whether they needed a cane or any other assistance to help with mobility. A second group of 95 patients with MS was used to confirm the team's results. The researchers found that patients who took longer than 6 seconds to walk 25 feet were more likely to be unemployed, have a change in occupation as a result of the disorder, use a cane for walking and require help with day-to-day activities, such as house cleaning and cooking. Of patients who took less than 6 seconds to walk to 25 feet, 59% were employed compared with 29% of patients who took longer than 6 seconds. Of the walkers who were faster than 6 seconds, 43% reported a change in occupation as a result of MS, compared with 71% of patients who took longer than 6 seconds. The participants who took 8 seconds or longer to walk 25 feet were more likely to be unemployed, divorced, require a walker for mobility and use Medicaid or Medicare. They were also 70% more likely to be unable to carry out day-to-day activities, such as grocery shopping, house cleaning, laundry and cooking. Myla Goldman of the University of Virginia (Charlottesville) said that these findings could be useful in providing "benchmarks" in the progression of MS. "We already know that the timed 25-foot walk test is a meaningful way to measure disability in MS. Our study builds on that research by providing a clearer idea of how walk time can provide information about how a person's disease progression and disability impacts their everyday activities and real-world function. Based on these findings, we propose that a timed 25-foot walk performance of 6 seconds or more, and 8 seconds or more represent meaningful benchmarks of MS progression," she said.

Excess protein production in brain cells may hold clues to rare disease . . . Scientists at Rutgers University (Newark, New Jersey) are studying the cause of a rare childhood disease that leaves children unable to walk by adolescence say new findings may provide clues to understanding more common neurodegenerative diseases like Alzheimer's and Parkinson's and developing better tools to treat them. In the online edition of Nature Neuroscience, Karl Herrup, Ronald Hart and Jiali Li in the Department of Cell Biology and Neuroscience, and Alexander Kusnecov, associate professor in behavioral and systems neuroscience in the Department of Psychology, provide new information about A-T disease, a rare genetic childhood disorder that occurs in an estimated 1 in 40,000 births. Children born with A-T disease have mutations in both of their copies of the ATM gene and cannot make normal ATM protein. This leads to problems in movement, coordination, equilibrium and muscle control as well as a number of other deficiencies outside the nervous system. Using mouse and human brain tissue studies, Rutgers researchers found that without ATM, the levels of a regulatory protein known as EZH2 go up. Looking through the characteristics of A-T disease in cells in tissue culture and in brain samples from both humans and mice with ATM mutation, they found that the increase in EZH2 was a major contributing factor to the neuromuscular problems caused by A-T. "We hope that this work will lead to new therapies to prevent symptoms in those with A-T disease," said Hart. "But on a larger level, this research provides a strong clue toward understanding more common neurodegenerative disorders that may use similar pathways. "It is a theme that has not yet been examined." While the EZH2 protein has been shown to help determine whether genes get turned on or off, altering the body's ability to perform biological functions, necessary for maintaining good health, the Rutgers study is the first time this protein – which can cause adverse health effects if there is too much of it – has been looked at in the mature nerve cells of the brain. By reducing the excess EZH2 protein that accumulated in mice genetically engineered with A-T disease, and creating a better protein balance within the nerve cells, Rutgers scientists found that mice exhibited improved muscle control, movement and coordination. In the study, mutant mice that had A-T disease and increased levels of EZH2 were "cured" when this excess EZH2 protein was reduced.

New 'mini-neural computer' discovered in brain . . . Neuroscientists have discovered that dendrites – branch-like projections of neurons in the brain – which were previously thought to be passive, actively process information. The discovery of this so-called mini-brain computer could provide a better understanding of neurological disorders. Neuroscientists from University College London (UCL) and the University of North Carolina at Chapel Hill made this discovery, which was published recently in the journal Nature, after years of research. "Suddenly, it's as if the processing power of the brain is much greater than we had originally thought," said Spencer Smith, assistant professor from the UNC School of Medicine. The team notes previous research has demonstrated that dendrites use molecules supporting electrical spikes in axons – nerve fibers that direct electrical pulses away from the cell body - to create electrical spikes themselves. However, it was unclear whether our normal brain activity uses those spikes from dendrites. The neuroscientists found that dendrites do actively process neuronal input signals on their own, acting as "mini-neural computers." To demonstrate this, the two teams of scientists on either side of the Atlantic Ocean conducted a series of detailed experiments that spanned years. A pipette attached to a dendrite in the brain of a mouse allowed the researchers to measure electrical activity, such as a dendritic spike. Credit: Courtesy of Spencer Smith. By attaching microscopic glass pipette electrodes to a neuronal dendrite in the brain of a mouse, the team was able to "listen" to the electrical signaling process. After beginning in senior author Michael Hausser's lab at UCL, the team at UNC continued the research by recording electrical signals from dendrites in the brains of mice that were either awake or anesthetized. Then, while the mice viewed visual stimuli on a screen, the scientists observed a strange pattern of electrical signals in the dendrites. In effect, they found that depending on the visual stimulus the mice viewed, the dendritic spikes "occurred selectively," showing that the dendrites were processing what the animal was viewing. When the team filled neurons with calcium dye, they were able to record visual evidence of the dendritic spikes, revealing that dendrites fired electrical spikes while other parts of the neuron did not. Smith notes that the spikes resulted from local processing within the dendrites: "All the data pointed to the same conclusion. The dendrites are not passive integrators of sensory-driven input; they seem to be a computational unit as well," he said. The researchers say that their findings could change the way the scientific community thinks about how neural circuitry works in the brain.

In blind people, light helps activate the brain . . . Light enhances brain activity during a cognitive task even in some people who are totally blind, according to a study conducted by researchers at the University of Montreal and Boston's Brigham and Women's Hospital (Boston). The findings contribute to scientists' understanding of everyone's brains, as they also revealed how quickly light impacts on cognition. "We were stunned to discover that the brain still respond significantly to light in these rare three completely blind patients despite having absolutely no conscious vision at all," said senior co-author Steven Lockley. "Light doesn't just allow us to see, it tells the brain whether it's night or day which in – turn ensures that our physiology, metabolism and behavior are synchronized with environmental time. For diurnal species like ours, light stimulates day-like brain activity, improving alertness and mood, and enhancing performance on many cognitive tasks," said senior co-author Julie Carrier. The results indicate that their brains can still "see," or detect, light via a novel photoreceptor in the ganglion cell layer of the retina, different from the rods and cones we use to see. Scientists believe, however, that these specialized photoreceptors in the retina also contribute to visual function in the brain even when cells in the retina responsible for normal image formation have lost their ability to receive or process light. A previous study in a single blind patient suggested that this was possible but the research team wanted to confirm this result in different patients. To test this hypothesis, the three participants were asked to say whether a blue light was on or off, even though they could not see the light. "We found that the participants did indeed have a non-conscious awareness of the light – they were able to determine correctly when the light was on greater than chance without being able to see it," said first author Gilles Vandewalle. The next steps involved looking closely at what happened to brain activation when light was flashed at their eyes at the same time as their attentiveness to a sound was monitored. "The objective of this second test was to determine whether the light affected the brain patterns associated with attentiveness – and it did," said first author Olivier Collignon. Finally, the participants underwent a functional MRI brain scan as they performed a simple sound matching task while lights were flashed in their eyes. "The fMRI further showed that during an auditory working memory task, less than a minute of blue light activated brain regions important to perform the task. These regions are involved in alertness and cognition regulation as well being as key areas of the default mode network," Vandewalle explained.

— Compiled by Robert Kimball, MDD Staff Writer