Gait instability and fractal dynamics of older adults with a “cautious” gait: why do certain older adults walk fearfully?
Introduction
Many older adults walk without any significant mobility impairment [1], [2], [3]. Among those older adults who do have a gait disturbance, the cause is often easily identifiable (e.g., Parkinson’s disease) [1], [2], [3], [4], [5]. There are, however, many older adults with an impaired gait that does not appear to be a result of any well defined disease [6]. In his review of patients attending a neurology clinic, Sudarsky found that the cause of the gait disturbance was “unknown”, even after neuro-imaging, in about 10–20% of older adults with a disturbed gait [3], [7]. In a study of the “oldest old” (age range 87–97 years) in The Netherlands, Bloem et al. observed that about 20% of those studied had a normal gait, 69% had a gait disorder due to known disease, and about 11% of the subjects had an idiopathic “senile gait disorder”, i.e., a gait disorder of unknown origin [8]. Interestingly, those subjects with a gait disorder of unknown origin had a higher risk of mortality during a 5 year follow up period, compared to the group of age-matched subjects who had a normal gait [8].
Nutt et al. coined the term “higher-level” gait disorders (HLGD) to refer to an altered gait that is not a result of lower extremity or peripheral dysfunction and can not be attributed to well defined chronic disease [5], [9]. One common example of a higher-level gait disorder is the idiopathic “cautious” gait of the elderly or the “senile gait” disorder [5], [9]. A cautious gait is typically marked by mild to moderate slowing, reduced stride length, and mild widening of the base of support [5]. Fear of falling, common among many older adults [5], [10], [11], [12], [13], presumably plays an important role in this cautious gait [5], [10], but the origin of the timid, reserved gait that is characteristic of so many elderly is not well understood. It is unclear if the changes in gait are related to a history of falls or a fear of future falls [12], whether these changes predispose to falls, or whether the appearance of a fearful gait is just coincidence (or secondary), i.e., the changes in gait are primary in origin and not just a result of fear. While a slow, guarded gait may be the response to a fear of falling, it does not, by itself, explain the exaggerated fear of falling seen in many older adults. Could other gait changes contribute to and explain the fear of falling?.
In a study of a relatively heterogeneous group of older adults living in assisted living facilities, Maki observed an intriguing dichotomy [14]. Fear of falling was related to gait speed, while falls were related to gait variability (those who fell during a 1 year follow-up period had increased gait variability, regardless of gait speed). Maki explained that subjects with a fear of falling walked more slowly, but fall risk was independent of gait speed and was modulated instead by gait variability. Subjects unable to regulate the stride-to-stride fluctuations in walking were more unstable and unsteady and more likely to fall. Similar results, at least with respect to the relationships between gait speed, gait variability and falls, were obtained in a prospective study of community living older adults [15]. However, to date, gait variability in older adults with HLGD and a cautious gait has not been studied and the relationship between fear of falling and unsteadiness in this population is not known. Is it possible that older adults with a cautious gait walk fearfully because they have an unsteady gait? In contrast to the general elderly population, where fear of falling appears to be related to fall history [11], [12], in this population, fear of falling may occur even in the absence of any fall history [10]. Perhaps increased unsteadiness could, in part, explain this fear of falling.
In the present study, we tested the hypothesis that gait variability, a marker of gait unsteadiness that is putatively unrelated to fear of falling [14], is increased among older adults with a HLGD and a cautious gait. Secondary aims of this study were: (1) to examine the factors associated with increased gait variability in order to better identify what contributes to fear of falling and the changes in gait dynamics in this population, and (2) to identify the factors that discriminate fallers and non-fallers in this population. As we describe below, our findings suggest that, in contrast to the general elderly population, a more complex relationship exists between fear of falling, gait instability, and falls in older adults with HLGD who walk fearfully.
Section snippets
Subjects
Twenty-five older adults who came to the Movement Disorders Unit at the Tel Aviv Sourasky Medical Center for evaluation of walking difficulties of unknown origin were studied. All patients were mobile and walked independently at the time of assessment and all underwent a thorough general and neurological examination.
Patients were excluded if the cause of their gait disturbance could be readily established. Thus, patients with a history of clinically established stroke, Parkinson’s disease,
Results
Fifty-three subjects participated in this study. Patients (n=25) and control (n=28) subjects were similar with respect to age (78.2±5.0 years versus 78.4±5.6 years, respectively, P=0.901), gender (68% women in both groups, P>0.99), height ( versus , respectively, P=0.486), weight ( versus , respectively, P=0.964) and the Charlson’s co-morbidity index (0.8±1.1 versus 0.6±1.0, respectively, P=0.173).
The clinical characteristics of the patient group are
Discussion
In this first study of the gait dynamics of older adults with a HLGD, we find three key results: (1) gait variability is markedly increased among older adults with a HLGD and fear of falling compared to control subjects of similar age. (2) Physical factors (e.g., muscle strength, balance disturbances) are not associated with the level of gait variability among the older adults with HLGD. Instead, neuro-psychological factors, especially fear of falling, and depression are significantly related
Acknowledgements
We thank the subjects for their participation, time and effort. This work was supported in part by NIH grants AG-14100, RR-13622, HD-39838 and AG-08812 and the US-Israel Binational Science Foundation. This work was presented in part at the Annual Meeting of the American Geriatrics Society, Washington DC, May 2002 and at the Seventh International Congress of Parkinson’s Disease and Movement Disorders, Miami, FL, November, 2002.
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