Harvard study links brain blood vessels, elderly falls

A stiffening of the aging brain's blood vessels reduces their ability to respond to changes in blood pressure, increasing the risk of falls by as much as 70 percent, researchers report. Although the change in the arteries is only one of many factors that lead to falls among the elderly, the findings provide a potential target for intervention, said Dr. Joe Verghese, a neurologist at Albert Einstein University College of Medicine who was not involved in the research. Treating high cholesterol, high blood pressure and diabetes, among other factors, can reduce the stiffening.
"Even if it accounts for only 10 percent to 15 percent of all falls, that's still large numbers that you are talking about," he said.
According to the Centers for Disease Control and Prevention, more than a third of adults over the age of 65 fall each year, and 30 percent of those suffer moderate to severe injuries, including hip fractures and traumatic brain injuries. Most elderly who are hospitalized with a hip fracture end up in a nursing home.
A variety of factors have been linked to falls, including diseases, foot problems, overmedication, environmental hazards — and abnormalities in the signaling potential of the brain's white matter, which controls both cognitive and motor functions, have also been linked. The new study was designed to demonstrate at least one mechanism by which these latter abnormalities could occur.
Dr. Farzaneh A. Sorond, a neurologist at Harvard University's Institute for Aging Research, and her colleagues studied 420 people older than the age of 65. The team used ultrasound to measure the flow of blood in the patients' brains while they were at rest and when they were breathing rapidly.
Heavy breathing increases carbon-dioxide levels and normally produces a dilation of the blood vessels, a phenomenon known as vasoreactivity. If blood vessels don't properly dilate under stress, the brain does not get enough oxygen and glucose.
The researchers also studied the patients' gait over a 12-foot course and had them keep a record of their falls. Poor gait is also a factor in falls. About 85 percent of 65-year-olds have a normal gait, but only 18 percent of 80-year-olds do.
The team reported in the journal Neurology that patients in the bottom fifth for vasoreactivity had a slower, worse gait than those in the top fifth and were 70 percent more likely to have suffered a fall during the study period.
"This gives us a window to intervene," Sorond said. "There is a lot of data, for example, that says (cholesterol-lowering) statins improve vasoreactivity. We hope to be funded to study that over the next five years."
The team also plans to do imaging studies to see if the low vasoreactivity is linked to problems with white matter.
The study was funded by the National Institute on Aging and a private donor.