VANCOUVER—Worsening gait may be associated with a decrease in cognitive function, according to several studies presented at the 2012 Alzheimer’s Association International Conference.
Stephanie Bridenbaugh, MD, and colleagues found that gait becomes slower and more variable as cognitive decline progresses. “Particularly, gait cycle time variability increases during cognitive dual tasking, compared to normal walking in those with mild cognitive impairment (MCI) and mild Alzheimer’s disease,” reported Dr. Bridenbaugh of the University Hospital Basel in Switzerland. “Early detection of these mobility impairments may be used as a tool to aid diagnosis of those in the earliest stages of cognitive impairment.”
Dr. Bridenbaugh’s retrospective study included 1,153 older adults (mean age, 78), including outpatients from the Memory Clinic of the University Hospital Basel. A total of 357 patients had healthy cognition, 309 had MCI, 219 had mild Alzheimer’s dementia, 230 had moderate Alzheimer’s dementia, and 38 had severe Alzheimer’s dementia. Participants’ gait was tested during normal walking as a single task and during a working memory and a semantic memory dual task.
Compared with single task normal walking, gait speed reduction was greater for the semantic memory task than for the working memory dual task in participants with healthy cognition, MCI, and mild Alzheimer’s disease. “Gait cycle time variability stayed relatively stable during the normal walking single task for those with healthy cognition, MCI, and mild Alzheimer’s disease, and yet increased during dual tasking, with the variability highest during the semantic memory dual task,” said Dr. Bridenbaugh. “This change was greater in those with MCI and mild Alzheimer’s disease than in those with healthy cognition. Age-stratified results showed that these changes in velocity and variability were not simply age-related.”
In a second study of 1,465 persons, ages 49 and older, Mohammad Ikram, MD, PhD, of Erasmus Medical Center, Rotterdam, the Netherlands, and colleagues found that processing speed was associated with the time aspect of gait, but not with space or variability. In addition, the investigators found that executive function was linked to variability and space, but not time. Furthermore, memory was not associated with any gait aspect.
“The magnitude of effect of these associations corresponds to a 10-year deterioration in gait,” said Dr. Ikram. “These data provide novel insights into the full clinical spectrum of brain pathology.”
In a third study, Rodolfo Savica, MD, of the Mayo Clinic in Rochester, Minnesota, and colleagues observed an association between reduced gait velocity, cadence, and stride length and global- and domain-specific cognitive decline in a study of 1,341 persons enrolled in the Mayo Clinic Study of Aging.
“Participants with lower cadence, velocity, and amplitude of the stride length experienced significantly larger declines in global cognition, memory, and executive function,” reported Dr. Savica. “Lower gait measures were also significantly associated with a greater decline on the Short Test of Mental Status…. Excluding persons with stroke, parkinsonism, vascular dementia, head injury, or normal pressure hydrocephalus from the analyses did not affect the results.”
In a fourth study, Lisa Silbert, MD, of the Oregon Health and Science University in Portland, and colleagues examined 19 persons without dementia and found that continuous in-home monitoring may be a more accurate measure of gait than single tests.
Participants walked faster when measured once in person than when they walked in their home under conditions of a continuous assessment system, which collected data using passive infrared motion-activity sensors averaged during a one-month period.
According to Dr. Silbert, slower walking speed as measured with the continuous in-home assessment technology was associated with smaller total brain size, although single walking speed measures were not. In addition, slower in-home walking speed was more closely associated with smaller hippocampus volumes than walking speed obtained during a single time point.
“Walking speed taken at a single time point may overestimate walking abilities in the elderly,” said Dr. Silbert. “Our data suggest that continuous in-home monitoring may provide a more accurate reflection of walking speed and may be more sensitive at detecting motor changes associated with future cognitive decline.”