Article

Falls in frail elderly are a common problem with a rising incidence.
Gait and postural instability are major risk factors for falling, particularly in
geriatric patients. As walking requires attention, cognitive impairments are
likely to contribute to an increased fall risk. An objective quantification of
gait and balance ability is required to identify persons with a high tendency to
fall. Recent studies have shown that stride variability is increased in elderly
and under dual task condition and might be more sensitive to detect fall risk
than walking speed. In the present study we complemented stride related measures
with measures that quantify trunk movement patterns as indicators of dynamic
balance ability during walking. The aim of the study was to quantify the effect
of impaired cognition and dual tasking on gait variability and stability in
geriatric patients. METHODS: Thirteen elderly with dementia (mean age: 82.6 +/-
4.3 years) and thirteen without dementia (79.4 +/- 5.55) recruited from a
geriatric day clinic, walked at self-selected speed with and without performing a
verbal dual task. The Mini Mental State Examination and the Seven Minute Screen
were administered. Trunk accelerations were measured with an accelerometer. In
addition to walking speed, mean, and variability of stride times, gait stability
was quantified using stochastic dynamical measures, namely regularity (sample
entropy, long range correlations) and local stability exponents of trunk
accelerations. RESULTS: Dual tasking significantly (p < 0.05) decreased walking
speed, while stride time variability increased, and stability and regularity of
lateral trunk accelerations decreased. Cognitively impaired elderly showed
significantly (p < 0.05) more changes in gait variability than cognitive intact
elderly. Differences in dynamic parameters between groups were more discerned
under dual task conditions. CONCLUSIONS: The observed trunk adaptations were a
consistent instability factor. These results support the concept that changes in
cognitive functions contribute to changes in the variability and stability of the
gait pattern. Walking under dual task conditions and quantifying gait using
dynamical parameters can improve detecting walking disorders and might help to
identify those elderly who are able to adapt walking ability and those who are
not and thus are at greater risk for falling.

Langue : ANGLAIS