By Eleanor McDermid, Senior medwireNews Reporter
A slow walking speed in elderly people is associated with the presence of ?-amyloid in their brains, research shows.
â€œA potential clinical implication of this observation is that slow gait, in the presence of subjective memory complaints, may represent an early marker of [Alzheimerâ€™s disease] pathology even in fully asymptomatic individualsâ€, say Natalia del Campo (University Hospital Toulouse, France) and study co-authors.
They note, however, that their findings do not prove that ?-amyloid deposition directly causes slower gait, whether by direct neurotoxicity or other mechanisms. This is just one possibility they raise, with others being that a common lifestyle factor causes both outcomes or that slow gait is a marker of a general frail condition in which the brain is more vulnerable to the effects of ?-amyloid deposition.
The 128 study participants were aged an average of 76 years, their cognitive performance ranged from normal to mildly impaired and 48.4% were amyloid positive on [18F]florbetapir positron emission tomography.
The participantsâ€™ gait speed was significantly associated with ?-amyloid deposition in 10 of 13 brain regions of interest. In multivariate analysis, the associations were strongest for the dorsal posterior putamen and the precuneus, the former of which fitted with the researchersâ€™ expectations.
â€œOut of all striatal subregions, the dorsal posterior putamen is uniquely interlinked with primary motor, premotor, supplementary motor, and primary somatosensory cortical areas and therefore plays a pivotal role in the modulation of motor circuitsâ€, they write in Neurology.
The presence of ?-amyloid explained between 1% and 9% of the variance in participantsâ€™ walking speed, depending on the specific brain region, even after accounting for variables including age, gender and APOE genotype.
The researchers note that the average speed of the participants was 1.06 m/s, and the gait of 11.7% was considered to be slow for their age (0.8 m/s).
They say their findings â€œimply that even gait speed scores considered as normal according to current conventionsâ€ may be a marker of Alzheimerâ€™s pathology.
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