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Biomedical subjects

Jeffrey M Hausdorff

Publications and source records attributed to Jeffrey M Hausdorff.

At least 19 recordsLinked to original sources
PubMed2007

Gait asymmetry in patients with Parkinson's disease and elderly fallers: when does the bilateral coordination of gait require attention?

While it is known that certain pathologies may impact on left-right symmetry of gait, little is known about the mechanisms that contribute to gait symmetry or how high in the hierarchy of the control of gait symmetry is regulated in humans. To assess the contribution of cognitive function to gait symmetry, we measured gait asymmetry (GA) in three subject groups, patients with Parkinson's disease (PD, n = 21), idiopathic elderly fallers (n = 15), and healthy elderly controls (n = 11). All subjects walked, under two walking conditions: usual walking and dual tasking (cognitive loading) condition. For each subject, the swing time (SW) was calculated and averaged across strides for the left and right feet (SWL and SWR). GA was defined as: 100 x /ln(SWR/SWL)/. For both the PD patients and the elderly fallers GA values were significantly higher during the usual walking condition, as compared with the control group (P < 0.01). In addition, for both the PD patients and the elderly fallers, GA significantly increased when they walked and performed a dual task, compared with the usual walking condition (P < 0.003). In contrast, dual tasking did not affect the GA of the healthy controls (P = 0.518). GA was associated with gait speed and gait variability, but no correlations were found between GA and the asymmetry of the classic PD motor symptoms. Thus, the results suggest that the ability to generate a steady, rhythmic walk with a bilaterally coordinated gait does not rely heavily on mental attention and cognitive resources in healthy older adults. In contrast, however, when gait becomes impaired and less automatic, GA apparently relies on cognitive input and attention.

Accidental Falls↗
PubMed2006

The role of mental function in the pathogenesis of freezing of gait in Parkinson's disease.

Freezing of gait (FOG) is a disabling episodic gait disturbance that is common among patients with Parkinsonism. FOG typically lasts a few seconds and is associated with a unique sensation: the patient feels that his feet are glued to the ground, causing him to remain in place despite making a concerted effort to overcome the motor block and move forward. Traditionally, FOG has been viewed as a motor symptom of advanced Parkinson's disease. Here we describe evidence which demonstrates that mental conditions also likely play an important role in the pathogenesis of FOG. Stress, anxiety, depression and cognitively challenging situations are associated with FOG, and may set the stage for and increase the likelihood that FOG occurs. A conceptual model that explains how mental conditions may modulate FOG is developed.

Gait↗
PubMed2006

Dual-tasking effects on gait variability: the role of aging, falls, and executive function.

The objectives of the present study were to test the hypothesis that the dual-tasking effect on gait variability is larger in healthy older adults than it is in healthy young adults; that this effect is larger in idiopathic elderly fallers than it is in healthy older adults; and that the dual-tasking effects on gait variability are correlated with executive function (EF). Young adults and older adults who were classified as fallers and nonfallers were studied. Gait speed, swing time, and swing time variability, a marker of fall risk, were measured during usual walking and during three different dual-tasking conditions. EF and memory were evaluated. When performing dual tasks, all three groups significantly decreased their gait speed. Dual tasking did not affect swing time variability in the young adults and in the nonfallers. Conversely, dual tasking markedly increased swing time variability in the fallers. While memory was similar in fallers and nonfallers, EF was different. The faller-specific response to dual tasking was significantly correlated with tests of EF. These findings demonstrate that dual tasking does not affect the gait variability of elderly nonfallers or young adults. In contrast, dual tasking destabilizes the gait of idiopathic elderly fallers, an effect that appears to be mediated in part by a decline in EF.

Accidental Falls↗
PubMed2006

Assessing fear of falling: Can a short version of the Activities-specific Balance Confidence scale be useful?

We present the process of further validation of the 16-item Activities-specific Balance Confidence scale (ABC-16) and a short version (ABC-6) derived by us, to assess balance confidence and fear of falling (FOF). The ABC-16 was administrated to three groups who were anticipated to have a range of balance confidence: 70 patients with higher level gait disorders (HLGDs), 68 healthy controls, and 19 patients with Parkinson's disease (PD). Item reduction was based on identifying items with the lowest scores (high FOF) among the patients. Internal consistency and discriminative validity were assessed using Cronbach's alpha and logistic regression, respectively. The intraclass correlation (ICC) between the short and long versions was assessed using a mixed model approach, accounting for the difference between the scores of the two versions. Six items were found to reflect the most frightening conditions, especially in the patient groups, and to form the short version (ABC-6). Internal consistency of the ABC-16 and ABC-6 were high in the three groups: Cronbach's alpha was between 0.83 and 0.91 and 0.81 and 0.90, respectively. Compared to the control group, the sensitivity of the ABC-16 was 96% for identification of patients with HLGDs (greatest FOF) and 58% for identification of PDs (moderate FOF), based only on the ABC scores. Similar values were obtained for the short version, i.e., 91% for HLGDs and 53% for PDs. ICCs between the short and the long versions was 0.88 (HLGDs), 0.83 (PDs), and 0.78 (Controls). To conclude, the short version of the ABC has properties analogous to the parent questionnaire and is apparently useful in assessing FOF.

Accidental Falls↗
PubMed2006

Marked alterations in the gait timing and rhythmicity of patients with de novo Parkinson's disease.

Little is known about the gait characteristics of subjects with de novo Parkinson's disease (PD). We hypothesized that alterations in the spatio-temporal characteristics of gait will already be quantifiable in these patients. The gait of 35 patients with idiopathic PD (mean age 60 years) who were in the early stages of the disease (Hoehn and Yahr stage 1.8 +/- 0.5, median 2.0, range 1.0-2.5) and were not yet treated with any anti-parkinsonian medications were compared with the gait of age- and sex-matched healthy controls (n = 22). The patients walked more slowly and with reduced swing times while also exhibiting increased left/right swing asymmetry and marked inconsistencies in the timing of gait. By contrast, significant group differences in the peak forces at heel-strike and in the stride-to-stride variability of the ground reaction forces (a reflection of muscle output consistency) were not observed. These findings indicate that in de novo PD, an altered gait pattern is observed, even though dramatic changes in the gait pattern may not yet be apparent visually (e.g. fairly intact gait speed). Furthermore, the results demonstrate that the observed alterations are not just side-effects of treatments or complications of the disease. Instead, there is evidence for motor programming deficits in gait, as revealed by increased gait variability and asymmetry in timing. PD apparently impinges on the regulation of a consistent gait rhythm, even early in the course of the disease when observed alterations are not the result of any pharmacologic treatment.

Aged↗
PubMed2005

"Brain Screen": A self-referral, screening program for strokes, falls and dementia risk factors.

BACKGROUND: Falls, strokes and dementia can be predicted and their occurrence can be delayed or even prevented by treatment of risk factors. The value of screening self-referred adults is unknown. OBJECTIVES: To assess whether a screening program of self-referred adults provides new and valuable medical information on risk factors for falls, stroke and dementia. METHOD: We examined 514 self-referred people (59% women, mean age 68+/-8 years (range 44-89) and 14+/-3 years of education) in our "Brain Screen" program. Participants completed detailed questionnaires and underwent a neurological examination, computerized gait analysis, carotid Duplex, serum lipid and homocysteine levels, a computerized neuropsychological battery (NeuroTrax) and the Mini-Mental State Exam. Information that was detected by "Brain Screen" was compared with the self-reported data. RESULTS: Unknown vascular risk factors detected by ""Brain Screen" included: high cholesterol in 44%, homocysteine > 10 micromol/L in 20%, >1 mm carotid intima-media thickness in 13%, and carotid narrowing (> 30%) in 2.2%. Unknown risk factors for falls were detected in 66% of the subjects who never fell. Of the 205 subjects (44%) who complained of memory decline, 28% had objective memory disturbances compared with their age group. Mild cognitive impairment (amnestic MCI) was clinically diagnosed in 17% of the population and dementia in 5%. CONCLUSION: Screening self-referred adults for falls, strokes and dementia risk factors detected significant unknown risk factors that can be treated in more than one-third of the participants. A national "Brain Screen" program can have significant impact on the health of the aging population.

Accidental Falls↗
PubMed2005

Shedding light on walking in the dark: the effects of reduced lighting on the gait of older adults with a higher-level gait disorder and controls.

OBJECTIVE: To study the effects of reduced lighting on the gait of older adults with a high level gait disorder (HLGD) and to compare their response to that of healthy elderly controls. METHODS: 22 patients with a HLGD and 20 age-matched healthy controls were studied under usual lighting conditions (1000 lumens) and in near darkness (5 lumens). Gait speed and gait dynamics were measured under both conditions. Cognitive function, co-morbidities, depressive symptoms, and vision were also evaluated. RESULTS: Under usual lighting conditions, patients walked more slowly, with reduced swing times, and increased stride-to-stride variability, compared to controls. When walking under near darkness conditions, both groups slowed their gait. All other measures of gait were not affected by lighting in the controls. In contrast, patients further reduced their swing times and increased their stride-to-stride variability, both stride time variability and swing time variability. The unique response of the patients was not explained by vision, mental status, co-morbidities, or the values of walking under usual lighting conditions. CONCLUSION: Walking with reduced lighting does not affect the gait of healthy elderly subjects, except for a reduction in speed. On the other hand, the gait of older adults with a HLGD becomes more variable and unsteady when they walk in near darkness, despite adapting a slow and cautious gait. Further work is needed to identify the causes of the maladaptive response among patients with a HLGD and the potential connection between this behavior and the increased fall risk observed in these patients.

Journal Article↗
PubMed2005

Effect of gait speed on gait rhythmicity in Parkinson's disease: variability of stride time and swing time respond differently.

BACKGROUND: The ability to maintain a steady gait rhythm is impaired in patients with Parkinson's disease (PD). This aspect of locomotor dyscontrol, which likely reflects impaired automaticity in PD, can be quantified by measuring the stride-to-stride variability of gait timing. Previous work has shown an increase in both the variability of the stride time and swing time in PD, but the origins of these changes are not fully understood. Patients with PD also generally walk with a reduced gait speed, a potential confounder of the observed changes in variability. The purpose of the present study was to examine the relationship between walking speed and gait variability. METHODS: Stride time variability and swing time variability were measured in 36 patients with PD (Hoehn and Yahr stage 2-2.5) and 30 healthy controls who walked on a treadmill at four different speeds: 1) Comfortable walking speed (CWS), 2) 80% of CWS 3) 90% of CWS, and 4) 110% of CWS. In addition, we studied the effects of walking slowly on level ground, both with and without a walker. RESULTS: Consistent with previous findings, increased variability of stride time and swing time was observed in the patients with PD in CWS, compared to controls. In both groups, there was a small but significant association between treadmill gait speed and stride time variability such that higher speeds were associated with lower (better) values of stride time variability (p = 0.0002). In contrast, swing time variability did not change in response to changes in gait speed. Similar results were observed with walking on level ground. CONCLUSION: The present results demonstrate that swing time variability is independent of gait speed, at least over the range studied, and therefore, that it may be used as a speed-independent marker of rhythmicity and gait steadiness. Since walking speed did not affect stride time variability and swing time variability in the same way, it appears that these two aspects of gait rhythmicity are not entirely controlled by the same mechanisms. The present findings also suggest that the increased gait variability in PD is disease-related, and not simply a consequence of bradykinesia.

Journal Article↗
PubMed2005

Gait variability: methods, modeling and meaning.

The study of gait variability, the stride-to-stride fluctuations in walking, offers a complementary way of quantifying locomotion and its changes with aging and disease as well as a means of monitoring the effects of therapeutic interventions and rehabilitation. Previous work has suggested that measures of gait variability may be more closely related to falls, a serious consequence of many gait disorders, than are measures based on the mean values of other walking parameters. The Current JNER series presents nine reports on the results of recent investigations into gait variability. One novel method for collecting unconstrained, ambulatory data is reviewed, and a primer on analysis methods is presented along with a heuristic approach to summarizing variability measures. In addition, the first studies of gait variability in animal models of neurodegenerative disease are described, as is a mathematical model of human walking that characterizes certain complex (multifractal) features of the motor control's pattern generator. Another investigation demonstrates that, whereas both healthy older controls and patients with a higher-level gait disorder walk more slowly in reduced lighting, only the latter's stride variability increases. Studies of the effects of dual tasks suggest that the regulation of the stride-to-stride fluctuations in stride width and stride time may be influenced by attention loading and may require cognitive input. Finally, a report of gait variability in over 500 subjects, probably the largest study of this kind, suggests how step width variability may relate to fall risk. Together, these studies provide new insights into the factors that regulate the stride-to-stride fluctuations in walking and pave the way for expanded research into the control of gait and the practical application of measures of gait variability in the clinical setting.

Journal Article↗
PubMed2005

Walking is more like catching than tapping: gait in the elderly as a complex cognitive task.

Walking is generally viewed as an automated, over-learned, rhythmic motor task and may even be considered the lower-limb analog of rhythmic finger tapping, another automated motor task. Thus, one might hypothesize that walking would be associated with a simple rhythmic task like tapping rather than with a complex motor task like catching. Surprisingly, however, we find that among older adults, routine walking has more in common with complex motor tasks, like catching a moving object, than it does with tapping. Tapping performance, including both the average tapping interval and the variability of tapping interval, was not significantly associated with any gait parameter (gait speed, average stride time and stride time variability). In contrast, catch game performance was significantly associated with measures of walking, suggesting that walking is more like catching than it is like tapping. For example, participants with a higher gait speed tended to have lower times to first move when catching, better catching accuracy, and less catching errors. Stride time variability was significantly associated with each of the measures of catching. Participants with a lower stride time variability (a more steady gait) had better catching accuracy, lower time to first move, fewer direction changes when moving the cursor to catch the falling object, and less catching errors. To understand this association, we compared walking performance to performance on the Stroop test, a classic measure of executive function, and tests of memory. Walking was associated with higher-level cognitive resources, specifically, executive function, but not with memory or cognitive function in general. For example, a lower (better) stride time variability was significantly associated with higher (better) scores on the Stroop test, but not with tests of memory. Similarly, when participants were stratified based on their performance on the Stroop test and tests of memory, stride time variability was dependent on the former, but not the latter. These findings underscore the interconnectedness of gait and cognitive function, indicate that even routine walking is a complex cognitive task that is associated with higher-level cognitive function, and suggest an alternative approach to the treatment of gait and fall risk in the elderly.

Aged↗
PubMed2005

Is freezing of gait in Parkinson's disease related to asymmetric motor function?

Freezing of gait (FOG) is a disabling phenomenon common in patients with advanced Parkinson's disease (PD). The cause of FOG is unclear. The objective of this study was to explore a novel hypothesis stating that FOG is related to asymmetric motor performance. We compared PD patients that experience FOG episodes (PD+FOG) with PD patients that do not (PD-FOG) and studied the relationship of FOG to asymmetry in gait and in rhythmic hand movement performance to determine whether potential FOG-related gait asymmetry is unique to walking or whether it is systemic. Subjects were tested in an "off" (unmedicated) and again in an "on" (medicated) state. Gait was more asymmetric in PD+FOG than in PD-FOG during "off" state (p = 0.005) and during "on" (p = 0.016). Rhythmicity of foot swing in one leg was correlated with the other leg in PD-FOG but not in PD+FOG. There was no difference in asymmetry in performance of rhythmic hand movements between the two groups. No correlation was found between asymmetry of clinical symptoms and gait asymmetry. Taken together, the results of this study suggest that bilateral uncoordinated gait and marked gait asymmetry, but not asymmetry in motor performance in general, are associated with FOG.

Cognition↗
PubMed2005

Treadmill walking as an external pacemaker to improve gait rhythm and stability in Parkinson's disease.

Recent reports suggest that external cueing improves stride length and gait speed in Parkinson's disease (PD). The purpose of the present study was to examine the influence of treadmill walking on gait variability. The 36 PD patients (Hoehn and Yahr stage 2--2.5) were compared to 30 controls. Subjects walked three times for 2 minutes each: (1) walking on level ground (unassisted), (2) walking on level ground while using a walker, and (3) walking on a treadmill. Stride time variability and swing time variability were significantly increased in the patients compared to the control subjects when walking on level ground with a walker. In both groups, the use of a walking aid did not significantly affect stride time variability or swing time variability, but the treadmill reduced stride time variability and swing time variability in the patients and in the controls. These results indicate that, during treadmill walking, PD subjects are able to walk with a less variable and more stable gait. Because the treadmill walking speed was set to the gait speed on level ground and because this effect was not seen with a walking aid, we suggest that the treadmill may be acting as an external cue to enhance gait rhythmicity and reduce gait variability.

Anthropometry↗
PubMed2005

Dual tasking, gait rhythmicity, and Parkinson's disease: which aspects of gait are attention demanding?

Cognitive function and the performance of a secondary, dual task may affect certain aspects of gait, but the relationships between cognitive function and gait are not well understood. To better understand the motor control of gait and the relationship between cognitive function and gait, we studied cognitive function and the effects of different types of dual tasking on the gait of patients with Parkinson's disease (PD) and controls, contrasting measures of gait automaticity and rhythmicity with other features. Patients with idiopathic PD (n=30; mean age 71.8 year) with moderate disease severity (Hoehn and Yahr Stage 2--3) were compared to age and gender-matched healthy controls (n=28). Memory and executive function were also assessed. In both groups, gait speed decreased in response to dual tasking, in a parallel fashion. For the PD group only, gait variability increased compared to usual walking. Executive function was significantly worse in the PD group, while memory was not different in the two groups. Executive function measures were significantly correlated with gait variability during dual tasking, but not during usual walking. These findings demonstrate that regulation of gait variability and rhythmicity is apparently an automatic process that does not demand attention in healthy adults. In patients with PD, however, this ability becomes attention-demanding and worsens when subjects perform secondary tasks. Moreover, the associations between executive function and gait variability suggest that a decline in executive function in PD may exacerbate the effects of dual tasking on gait, potentially increasing fall risk.

Aged↗
PubMed2004

Gait unsteadiness and fall risk in two affective disorders: a preliminary study.

BACKGROUND: In older adults, depression has been associated with increased fall risk, but the reasons for this link are not fully clear. Given parallels between major depression and Parkinson's disease, we hypothesized that major depression and related affective disorders would be associated with impairment in the ability to regulate the stride-to-stride fluctuations in gait cycle timing. METHODS: We measured stride-to-stride fluctuations of patients with two forms of mood disorders, unipolar major depressive disorder (MDD) and bipolar disorder, and compared their gait to that of a healthy control group. The primary outcomes were two measures of gait unsteadiness that have been associated with fall risk: stride time variability and swing time variability. RESULTS: Compared to the control group, the two patient groups tended to walk more slowly and with decreased swing time and increased stride time. However, none of these differences was statistically significant. Compared to the control group, swing time variability was significantly larger in the subjects with bipolar disorder (p < 0.0001) and in the subjects with MDD (p < 0.0004). CONCLUSIONS: Patients with MDD and patients with bipolar disorder display gait unsteadiness. This perturbation in gait may provide a mechanistic link connecting depression and falls. The present findings also suggest the possibility that measurement of variability of gait may provide a readily quantifiable objective approach to monitoring depression and related affective disorders.

Accidental Falls↗
PubMed2004

Falls and freezing of gait in Parkinson's disease: a review of two interconnected, episodic phenomena.

Falls and freezing of gait are two "episodic" phenomena that are common in Parkinson's disease. Both symptoms are often incapacitating for affected patients, as the associated physical and psychosocial consequences have a great impact on the patients' quality of life, and survival is diminished. Furthermore, the resultant loss of independence and the treatment costs of injuries add substantially to the health care expenditures associated with Parkinson's disease. In this clinically oriented review, we summarise recent insights into falls and freezing of gait and highlight their similarities, differences, and links. Topics covered include the clinical presentation, recent ideas about the underlying pathophysiology, and the possibilities for treatment. A review of the literature and the current state-of-the-art suggests that clinicians should not feel deterred by the complex nature of falls and freezing of gait; a careful clinical approach may lead to an individually tailored treatment, which can offer at least partial relief for many affected patients.

Accidental Falls↗
PubMed2004

Heart rate dynamics during three forms of meditation.

OBJECTIVE: This study was designed to quantify and compare the instantaneous heart rate dynamics and cardiopulmonary interactions during sequential performance of three meditation protocols with different breathing patterns. BACKGROUND: We analyzed beat-to-beat heart rate and continuous breathing signals from 10 experienced meditators (4 females; 6 males; mean age 42 years; range 29-55 years) during three traditional interventions: relaxation response, breath of fire, and segmented breathing. RESULTS: Heart rate and respiratory dynamics were generally similar during the relaxation response and segmented breathing. We observed high amplitude, low frequency (approximately 0.05-0.1 Hz) oscillations due to respiratory sinus arrhythmia during both the relaxation response and segmented breathing, along with a significantly (p<0.05) increased coherence between heart rate and breathing during these two maneuvers when compared to baseline. The third technique, breath of fire, was associated with a different pattern of response, marked by a significant increase in mean heart rate with respect to baseline (p<0.01), and a significant decrease in coherence between heart rate and breathing (p<0.05). CONCLUSIONS: These findings suggest that different meditative/breathing protocols may evoke common heart rate effects, as well as specific responses. The results support the concept of a "meditation paradox," since a variety of relaxation and meditative techniques may produce active rather than quiescent cardiac dynamics, associated with prominent low frequency heart rate oscillations or increases in mean resting heart rate. These findings also underscore the need to critically assess traditional frequency domain heart rate variability parameters in making inferences about autonomic alterations during meditation with slow breathing.

Adult↗
PubMed2003

Gait dynamics in Parkinson's disease: relationship to Parkinsonian features, falls and response to levodopa.

OBJECTIVES: Patients with Parkinson's disease (PD) have an increased risk of falling that has yet to be fully explained. To better understand the gait disturbance in PD and the factors that contribute to falls, we quantitatively evaluated: (1) the relationship between gait variability (a marker of fall risk in other populations), fall history, and other parkinsonian features, and (2) the effects of levodopa on these relationships. METHODS: The average stride time and stride-to-stride variability were measured using force-sensitive insoles during comfortable walking. Fall frequency, motor control, function, and mental health were measured using the Unified Parkinson's Disease Rating Scale (UPDRS), the Mini-Mental State Exam (MMSE), and the timed motor tests of the Core Assessment Program for Intracerebral Transplantations (CAPIT) in 32 subjects with idiopathic PD, in an "off" (unmedicated) state and again in an "on" (medicated) state. RESULTS: Average stride time was not associated with any UPDRS or CAPIT measure and was similar in fallers and non-fallers in "off" and "on" states (p>0.27). Stride time variability was significantly associated with fall frequency as well as with total scores on the CAPIT and the UPDRS, ADL abilities, and motor function. Stride time variability and falls were not related to tremor, rigidity or bradykinesia in the "off" state. 41% of subjects reported one or more falls. Stride time variability was 8.8+/-7.9% in fallers and 4.2+/-1.3% in non-fallers (p<0.009). Stride time variability significantly improved in response to levodopa, both in fallers and non-fallers, but remained increased in fallers (vs. non-fallers). CONCLUSIONS: The patho-physiology responsible for impaired stride-to-stride regulation of gait timing is apparently independent of other cardinal features of PD, i.e., tremor, rigidity, or bradykinesia, but is responsive to levodopa. Stride-to-stride variability is especially impaired among PD subjects with a history of falls, suggesting, for the first time, the possibility of exaggerated impairment of internal clock function in PD fallers.

Activities of Daily Living↗