Cognitive processes related to gait velocity

Mar 27 2006

Psychologists wanting to help old people safely cross the street and otherwise ambulate around this busy world have found that from age 70 and up, safe walking may require solid "executive control" (which includes attention) and memory skills.

For the old, slow gait is a significant risk factor for falls, many of which result in disabling fractures, loss of independence or even death. The finding may help explain why cognitive problems in old age, including dementia, are associated with falls. Cognitive tests could help doctors assess risk for falls; conversely, slow gait could alert them to check for cognitive impairment. The findings are in the March issue of Neuropsychology, which is published by the American Psychological Association (APA).

Roee Holtzer, PhD, and his colleagues conducted a cross-sectional study of 186 cognitively normal, community-dwelling adults aged 70 and older at New York City's Albert Einstein College of Medicine. Gait speed was tested with and without interference. In the interference conditions, participants had to walk while reciting alternate letters of the alphabet.

Performance on cognitive tests of executive control and memory, and to a lesser extent of verbal ability, predicted "gait velocity" (walking speed) tested without interference. For gait velocity tested with interference, only executive control and memory were predictive. Adding interference to the tests of gait allowed the researchers to better simulate the real world, in which walkers continually deal with distractions. The authors conclude that executive control and memory function are important when the individual has to walk in a busy environment.

The findings suggest that in old age, walking involves higher-order executive-control processes. That is, the intersecting cognitive and motor processes involved in walking may both rely on a common brain substrate, or set of structures. As a result, changes in that substrate would affect both cognition and gait.

Falls are a serious public-health issue for an aging population. Many older people are aging in the suburbs, where traffic conditions are often not designed for pedestrians of any age. And in cities, traffic lights at busy intersections are not usually timed to give people with slower perceptions and reflexes more time to safely cross the street.

Holtzer says that risk assessment and prevention programs for falls, which have typically focused on balance, strength and gait but not cognitive function, have had limited success. Given the new research, he posits that cognitive and neuropsychological performance, plus gait, could both factor into risk assessment and intervention design. What's more, cognitive rehabilitation and/or medication targeting cognitive functions such as executive control and memory might, among other benefits, reduce the risk of falling in people at risk.

Future study is needed to follow people through the life span to see how age affects the relationship between cognitive functions and gait. Holtzer cites evidence that gait is more automatic and less effortful in young than old people and points out that even within the narrow age range of his study's participant sample, each additional year tightened the relationship between cognitive function and gait velocity.