Each system included wall-mounted motion sensors placed in every room, door-mounted magnetic contact sensors, and wireless transceivers that sent the data to a computer in the home. The scientists then determined the number of times the sensors fired each minute during 24-hour blocks of time to create an overall activity level score for each participant.
Researchers found "the impaired subjects had more variability in their walking times than the healthy elderly group," and this variability was greater in the afternoon than in the morning, according to the study. This is consistent with earlier studies suggesting that variability in motor measures may predict later-onset dementia.
In addition, the elders with mild cognitive impairment were more variable in their activity during the day compared to their healthy counterparts. This inconsistency was "the most striking difference between the groups. Even with as few subjects as we had, the groups were clearly separated by the variability of these measures," Hayes noted. Differences were detectable after only four weeks of monitoring.
Such differences often are less obvious, if not imperceptible, during a typical clinical examination. In fact, many elders' desire to perform well during doctor visits make them walk faster than their normal daily paces, masking changes that may be clinically relevant, researchers say.
Hayes and her colleagues predict that as healthy elders begin to develop cognitive impairment, they become more variable day to day or even hour to hour, and that "this variability may provide an early marker that can be used to predict the later onset of dementia in a single individ
Source:Oregon Health & Science University