Alzheimer's and Lewy body disease have unique signatures of gait impairment which may reflect underlying pathology, an exploratory study suggested.
Compared with people who have Alzheimer's disease, people with Lewy body disease vary their step time and length and are asymmetric when they move, reported Riona McArdle, PhD, of Newcastle University in England, and co-authors, in Alzheimer's & Dementia.
The research shows for the first time that gait may provide clues to help distinguish between Alzheimer's disease and Lewy body dementia. "This lays a foundation to push forward research looking at walking as a potential early marker for dementia, and a supportive marker for differential diagnosis of dementia subtypes," McArdle told 鶹ý.
"Research has previously shown that people with dementia have walking problems; however, there was little knowledge when it came to what kind of walking problems specific types of dementia have," she added. Recent reports have shown that of Parkinson's disease, for example, and that can differentiate idiopathic normal-pressure hydrocephalus from progressive supranuclear palsy.
In the new study, McArdle and colleagues assessed the gait of 110 people: 29 cognitively normal older adults, 36 people diagnosed with Alzheimer's disease, and 45 people diagnosed with Lewy body disease. Because people with dementia with Lewy bodies and Parkinson's disease dementia had no significant differences in any gait characteristics, the researchers combined those participants to form a Lewy body disease group to increase statistical power. People in the Alzheimer's and Lewy body disease groups had cognitive dysfunction that ranged from mild cognitive impairment to moderate dementia, but mostly had mild dementia.
The study used an instrumented walkway that captured footsteps as participants walked across it at a comfortable pace during six 10-meter walks. The walkway quantified 16 gait characteristics of five independent domains of walking -- pace, rhythm, variability, asymmetry, and postural control.
The Lewy body disease group demonstrated greater impairments in asymmetry and variability compared with Alzheimer's patients: they changed how long it took to take a step and the length of their step more frequently, and their right and left footsteps were different from each other. Both Lewy body disease and Alzheimer's patients were more impaired in pace and variability domains than cognitively normal older adults.
Executive dysfunction explained 11% of variance for gait variability in Lewy body disease, and global cognitive impairment explained 13.5% of variance in Alzheimer's disease, the researchers determined, suggesting that gait impairments may reflect disease-specific cognitive profiles. "These exploratory findings support the theory of interacting cognitive-motor networks, as the gait-cognition relationship may reflect cognitive control over motor networks," the team wrote.
This research is pioneering for dementia, observed James Pickett, PhD, of the Alzheimer's Society in London, England, which funded the research. "It shows promise in helping to establish a novel approach to accurately diagnose different types of dementia," he said in a statement.
These findings pave the way to more novel work looking at walking in dementia subtypes, McArdle added. "In particular, we will look at inexpensive wearable technology to see if this can show these different walking patterns in clinical environments and within peoples' own homes," she said.
A larger replication study with well-defined Alzheimer's and Lewy body disease groups is needed to establish gait as a proxy for underlying neuropathology and possibly as a diagnostic tool, the researchers noted. Besides small sample size, the lack of diagnostic certainty was a limitation in this exploratory study. While imaging and recognized biomarkers were used to support clinical diagnoses of Alzheimer's and Lewy body disease, they were not always available. The researchers also could not account for comorbidities that might affect gait, such as arthritis or cerebrovascular lesions.
Disclosures
This work was supported by the Alzheimer's Society and the National Institute for Health Research (NIHR) Newcastle Biomedical Research Centre based at Newcastle upon Tyne Hospitals NHS Foundation Trust and Newcastle University.
The authors declared no conflict of interests.
Primary Source
Alzheimer's & Dementia
McArdle R, et al "Do Alzheimer's and Lewy body disease have discrete pathological signatures of gait?" Alzheimer's & Dementia 2019; DOI: https://doi.org/10.1016/j.jalz.2019.06.4953.