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Biomedical subjects

J M Hausdorff

Publications and source records attributed to J M Hausdorff.

At least 19 recordsLinked to original sources
PubMed2005

Falls in outpatients with Parkinson's disease: frequency, impact and identifying factors.

Falls are one of the most serious complications of gait disturbances in patients with Parkinson's disease (PD). Among previous reports, the percentage of patients with PD who fall varies between 38% to 68%. We sought to determine the frequency of falls and the factors associated with falls in a group of patients with idiopathic PD who attended an outpatient, tertiary movement disorders clinic. 350 ambulatory, non-demented patients (230 males) were studied. Mean age was 69.7+/-10.6 years (range: 43-97 yrs) and mean duration of PD symptoms was 8.6+/- 6.2 years (range: 1-33 yrs). Assessments included characterization of demographics, disease duration, disease severity as measured by the Hoehn and Yahr Scale (H&Y), co-morbidities, the presence of depressive symptoms, the presence of urinary incontinence, use of anti-parkinsonian medications, and two performance-based tests of balance and gait (tandem standing and Timed Up & Go). Fall history was determined during three time periods: previous week, previous month, and previous year. Univariate and multivariate logistic regression models were applied to evaluate the relationship between the above-mentioned factors and falls. 46% of the subjects reported at least one fall in the previous year and 33% reported 2 or more falls and were classified as Fallers. Fallers had significantly more prolonged and advanced PD compared with Non-fallers (p=0.001 and p<0.001, respectively). Urinary incontinence was the factor most closely associated with falls (crude and adjusted OR were 1.95 and 5.89, respectively). Other factors significantly associated with fall status included increased Timed Up & Go times and increased PD duration. These findings confirm that falls are a common problem among patients with advanced PD and suggest easily measurable features that may be used to prospectively identify those PD patients with the greatest risk of falls.

Accidental Falls↗
PubMed2005

Clinical characteristics of elderly patients with a cautious gait of unknown origin.

OBJECTIVE: To evaluate and systematically characterize a group of older adults with disturbed gait of unknown origin. DESIGN: Cross-sectional study. SETTING: Outpatient clinic in a movement disorders unit. PARTICIPANTS: Twenty-five patients (mean age 78.4 years) with a disturbed gait of unknown origin were compared with twenty-eight age matched "healthy" controls (mean age 78.2). MEASUREMENT: Detailed medical history, geriatric and neurological assessments. RESULTS: Patients walked more slowly (P<0.0001) and with shorter strides (P<0.0001) compared with controls. Muscle strength was lower, and static and dynamic balance and gait performance were worse among the patients (P<0.0001). The patients also tended to be more depressed (P<0.0001),more anxious (P<0.002), had a greater fear of falling (P<0.0001) and had lower scores on the Mini-Mental State Examination (P<0.005). There was no difference in the frequency of cerebellar or pyramidal signs in the two groups. However, neurological testing revealed that extrapyramidal (P<0.0001) and frontal release signs (P<0.0001) were more common among the patients. Neuroradiological findings were rare among the patients and they did not explain the changes in gait speed or fear of falling. CONCLUSIONS: Older adults with a disturbed gait of unknown origin appear to share common characteristics. They walk more slowly than "healthy" controls with increased unsteadiness and with excessive fear of falling. The extrapyramidal, frontal lobe, and limbic systems apparently play an important role, to different degrees, in what can be viewed as a multisystem neurodegenerative syndrome clearly different from "aging."

Aged↗
PubMed2005

Gait instability and fractal dynamics of older adults with a "cautious" gait: why do certain older adults walk fearfully?

Many older adults walk with a cautious and impaired gait of unknown origin, however, the relationship between fear of falling and the observed gait changes is not well understood. To better understand the "cautious" gait of the elderly, we tested the hypothesis that temporal gait variability, putatively a marker of intrinsic walking unsteadiness, is increased among older adults with a cautious gait and a higher-level gait disorder (HLGD), an altered gait that cannot be attributed to a well-defined cause. Twenty-five older adults (mean age: 78 years) with a HLGD were compared to healthy controls of similar age and sex (n=28). The clinical characteristics (e.g., neurological status, fear of falling), the magnitude of the stride-to-stride variations in gait cycle timing (a measure of temporal gait variability), and a fractal index of gait (a measure of the stride dynamics independent of the magnitude of the variability) were studied in both groups. Gait variability was significantly increased (P<0.0001) in HLGD subjects (52+/-26 ms) compared to controls (27+/-9 ms). Changes in frontal lobe and extra-pyramidal function were also found in the patient group. Among HLGD subjects, gait variability was not associated (P>0.05) with age, gender, MMSE score, muscle strength, # of co-morbidities, balance, cerebellar signs, or pyramidal signs, but was significantly associated with scores on the Geriatric Depression Scale (r=0.46, P<0.02) and fear of falling (r=0.69, P<0.0001). Among HLGD subjects, only a fractal index was significantly different in fallers and non-fallers. These findings underscore the idea that the gait changes in older adults who walk with fear may be an appropriate response to unsteadiness, are likely a marker of underlying pathology, and are not simply a physiological or psychological consequence of normal aging.

Accidental Falls↗
PubMed2004

R-R interval variation in Parkinson's disease and multiple system atrophy.

OBJECTIVE: To investigate whether the cardiac R-R interval variation (RRIV) is of value in differentiating patients with Parkinson's disease (PD) from multiple system atrophy (MSA). BACKGROUND: RRIV assessment is a simple procedure, reflecting mainly vagal efferent activity. Reduced RRIV was reported in MSA. METHODS: RRIV at rest and after 120 s of deep breathing was assessed blindly to clinical diagnosis in 22 PD and 20 MSA patients. The results were compared with data from 23 age-matched healthy subjects. RESULTS: RRIV at rest was 7.1 +/- 2.7% in PD and 9.7 +/- 7.2% in MSA, increasing after deep breathing to 11.2 +/- 6.3 and 12.3 +/- 6.6% correspondingly. The frequency of the RRIV abnormalities in the PD group (4/22, 18.2%) and MSA (6/20, 30%) were higher than among controls (P < 0.004). CONCLUSIONS: RRIV, either at rest or after deep breathing, may be abnormal both in PD and MSA, but does not distinguish between these disorders.

Aged↗
PubMed2003

Impaired regulation of stride variability in Parkinson's disease subjects with freezing of gait.

Patients with Parkinson's disease (PD) often experience freezing of gait, a debilitating phenomenon during which the subject suddenly becomes unable to start walking or to continue to move forward. Little is known about the gait of those subjects with PD who experience freezing of gait or the pathophysiology of freezing. One possibility is that freezing of gait is a truly paroxysmal phenomenon and that the usual walking pattern of subjects who experience freezing of gait is not different than that of other patients with PD who do not experience these transient episodes of freezing of gait. On the other hand, a recent study noted gait changes just prior to freezing and concluded that dyscontrol of the cadence of walking contributes to freezing. To address this question, we compared the gait of PD subjects with freezing of gait to PD subjects without freezing of gait. Given the potential importance of the dyscontrol of the cadence of walking in freezing, we focused on two aspects of gait dynamics: the average stride time (the inverse of cadence, a measure of the walking pace or rate) and the variability of the stride time (a measure of "dyscontrol," arrhythmicity and unsteadiness). We found that although the average stride time was similar in subjects with and without freezing, stride-to-stride variability was markedly increased among PD subjects with freezing of gait compared to those without freezing of gait, both while "on" (P<0.020) and "off" (P<0.002) anti-parkinsonian medications. Further, we found that increased gait variability was not related to other measures of motor control (while off medications) and levodopa apparently reduced gait variability, both in subjects with and without freezing. These results suggest that a paradigm shift should take place in our view of freezing of gait. PD subjects with freezing of gait have a continuous gait disturbance: the ability to regulate the stride-to-stride variations in gait timing and maintain a stable walking rhythm is markedly impaired in subjects with freezing of gait. In addition, these findings suggest that the inability to control cadence might play an important role in this debilitating phenomenon and highlight the key role of dopamine-mediated pathways in the stride-to-stride regulation of walking.

Aged↗
PubMed2003

Relationship between freezing of gait (FOG) and other features of Parkinson's: FOG is not correlated with bradykinesia.

BACKGROUND: The pathophysiology of freezing of gait (FOG) is unclear. OBJECTIVE: To assess the relationships between FOG and other parkinsonian features in Parkinson's disease (PD), focusing on levodopa effects. METHODS: Nineteen PD patients with significant FOG in "off" were assessed while "off" and "on". Three observers independently viewed videotapes of a 130-m walk and scored FOG frequency. The Unified Parkinson's disease Rating Scale was used to evaluate clinical state. RESULTS: FOG frequency was not correlated with other parkinsonian features in "off" and only with speech and writing in "on". Levodopa significantly decreased FOG frequency (p<0.001). This reduction was strongly correlated with improvement of tremor (R=0.80, p<0.01) and speech (R=0.62, p<0.05), but not with improvement in rigidity, bradykinesia, or balance. CONCLUSION: Levodopa decreases FOG in PD. FOG is apparently an independent motor symptom, caused by a paroxysmal pathology that is different from that responsible for bradykinesia, rigidity or postural instability.

Antiparkinson Agents↗
PubMed2003

Characterization of freezing of gait subtypes and the response of each to levodopa in Parkinson's disease.

To assess the effect of levodopa on distinct freezing of gait (FOG) subtypes in patients with 'off' FOG. Nineteen patients (12 men, mean age 62.0 +/- 8.4 years) with Parkinson's disease and clinically significant FOG during 'off' states were videotaped whilst walking 130 m during 'off' and 'on' states. Three independent observers characterized the type, duration, and clinical manifestations and quantified FOG by analyzing the videotapes. Their combined mean scores were used for statistical analysis. The intra-class correlation coefficient assessed inter-observer reliability. Wilcoxon and Friedman tests evaluated differences in mean frequencies of FOG characteristics. During 'off' states, FOG was elicited by turns (63%), starts (23%), walking through narrow spaces (12%) and reaching destinations (9%). These respective values were only 14, 4, 2 and 1% during 'on' states (P < 0.011). Moving forward with very small steps and leg trembling in place were the most common manifestations of FOG; total akinesia was rare. Most FOG episodes took <10 s and tended to be shorter during 'on' states. Levodopa significantly decreased FOG frequency (P < 0.0001) and the number of episodes with akinesia (P < 0.001). Distinction amongst FOG subtypes enables evaluation of distinctive therapeutic response. Levodopa helps in reducing the frequency and duration of 'off'-related FOG.

Aged↗
PubMed2001

When human walking becomes random walking: fractal analysis and modeling of gait rhythm fluctuations.

We present a random walk, fractal analysis of the stride-to-stride fluctuations in the human gait rhythm. The gait of healthy young adults is scale-free with long-range correlations extending over hundreds of strides. This fractal scaling changes characteristically with maturation in children and older adults and becomes almost completely uncorrelated with certain neurologic diseases. Stochastic modeling of the gait rhythm dynamics, based on transitions between different "neural centers", reproduces distinctive statistical properties of the gait pattern. By tuning one model parameter, the hopping (transition) range, the model can describe alterations in gait dynamics from childhood to adulthood including a decrease in the correlation and volatility exponents with maturation.

Adolescent↗
PubMed2001

Disparate effects of socioeconomic status on physical function and emotional well-being in older adults.

We tested the hypothesis that among community living older adults with relatively low and high socioeconomic status (SES), low SES is associated with both poorer emotional well-being and physical function. Ambulatory, community living older men and women (70-89 years of age) were recruited from outpatient geriatric assessment clinics in relatively high socioeconomic areas of greater Boston (High SES, N=47), and from an urban senior center in the inner city (Low SES, N=66). We assessed health status, mental health, upper and lower extremity strength and physical function. We found that health status was not significantly different in the two groups. Quadriceps strength (Low SES: 199+/-57 N; High SES: 190+/-56 N; p=0.531) and Up and Go times (Low SES: 14.3+/-3.1 sec; High SES: 16.7+/-9.5 sec; p=0.068) were not significantly different in the two groups, while grip strength was slightly higher in the Low SES group (Low SES: 22.8+/-6.45 kg; High SES: 20.07+/-7.55 kg; p=0.049). In contrast, subjects with Low SES tended to have an increased tendency towards depression. Scores on the Geriatric Depression Scale were 3.8+/-3.0 in Low SES, and 1.8+/-2.8 in High SES (p<0.001). We conclude that while health status and physical function were not worse in subjects with low SES, emotional well-being was markedly less compared to seniors with high SES. SES may have disparate effects on physical function and mental health, perhaps due to different compensatory mechanisms.

Activities of Daily Living↗
PubMed2001

Gait variability and fall risk in community-living older adults: a 1-year prospective study.

OBJECTIVE: To test the hypothesis that increased gait variability predicts falls among community-living older adults attending an outpatient clinic. DESIGN: Prospective, cohort study. SETTING: Three outpatient geriatric clinics. PARTICIPANTS: Fifty-two community-living, ambulatory men and women aged > or = 70 years. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjects walked at a normal pace for up to 6 minutes wearing force-sensitive insoles that measured the gait rhythm on a stride-to-stride basis. Afterward, subjects reported fall status on a weekly basis for 1 year. The primary outcomes were the association between measures of the stride-to-stride fluctuations in gait rhythm and (1) subsequent falls during a 12-month follow-up period and (2) potential contributing factors. RESULTS: Almost 40% of the subjects reported falling during the 12-month follow-up period. Stride time variability was 106 +/- 30 ms in subjects who subsequently fell (n = 20) and 49 +/- 4 ms in those who did not experience a fall (n = 32) during the 12-month follow-up period (p <.04). Logistic regression also showed that stride time variability predicted falls (p <.05). Stride time variability correlated significantly with multiple factors including strength, balance, gait speed, functional status, and even mental health, but these other measures did not discriminate future fallers from nonfallers. CONCLUSIONS: These findings show both the feasibility of obtaining stride-to-stride measures of gait timing in the ambulatory setting and the potential use of gait variability measures in augmenting the prospective evaluation of fall risk in community-living older adults.

Accidental Falls↗
PubMed2001

Etiology and modification of gait instability in older adults: a randomized controlled trial of exercise.

Increased gait instability is common in older adults, even in the absence of overt disease. The goal of the present study was to quantitatively investigate the factors that contribute to gait instability and its potential reversibility in functionally impaired older adults. We studied 67 older men and women with functional impairment before and after they participated in a randomized placebo-controlled, 6-mo multimodal exercise trial. We found that 1) gait instability is multifactorial; 2) stride time variability is strongly associated with functional status and performance-based measures of function that have previously been shown to predict significant clinical outcomes such as morbidity and nursing home admission; 3) neuropsychological status and health-related quality of life play important, independent roles in gait instability; and 4) improvement in physiological capacity is associated with reduced gait instability. Although the etiology of gait instability in older persons with mild-moderate functional impairment is multifactorial, interventions designed to reduce gait instability may be effective in bringing about a more consistent and more stable walking pattern.

Aged↗
PubMed2001

Randomized trial of progressive resistance training to counteract the myopathy of chronic heart failure.

Chronic heart failure (CHF) is characterized by a skeletal muscle myopathy not optimally addressed by current treatment paradigms or aerobic exercise. Sixteen older women with CHF were compared with 80 age-matched peers without CHF and randomized to progressive resistance training or control stretching exercises for 10 wk. Women with CHF had significantly lower muscle strength (P < 0.0001) but comparable aerobic capacity to women without CHF. Exercise training was well tolerated and resulted in no changes in resting cardiac indexes in CHF patients. Strength improved by an average of 43.4 +/- 8.8% in resistance trainers vs. -1.7 +/- 2.8% in controls (P = 0.001), muscle endurance by 299 +/- 66% vs. 1 +/- 3% (P = 0.001), and 6-min walk distance by 49 +/- 14 m (13%) vs. -3 +/- 19 m (-3%) (P = 0.03). Increases in type I fiber area (9.5 +/- 16%) and citrate synthase activity (35 +/- 21%) in skeletal muscle were independently predictive of improved 6-min walk distance (r2 = 0.78; P = 0.0024). High-intensity progressive resistance training improves impaired skeletal muscle characteristics and overall exercise performance in older women with CHF. These gains are largely explained by skeletal muscle and not resting cardiac adaptations.

Adaptation, Physiological↗
PubMed2000

PhysioBank, PhysioToolkit, and PhysioNet: components of a new research resource for complex physiologic signals.

The newly inaugurated Research Resource for Complex Physiologic Signals, which was created under the auspices of the National Center for Research Resources of the National Institutes of Health, is intended to stimulate current research and new investigations in the study of cardiovascular and other complex biomedical signals. The resource has 3 interdependent components. PhysioBank is a large and growing archive of well-characterized digital recordings of physiological signals and related data for use by the biomedical research community. It currently includes databases of multiparameter cardiopulmonary, neural, and other biomedical signals from healthy subjects and from patients with a variety of conditions with major public health implications, including life-threatening arrhythmias, congestive heart failure, sleep apnea, neurological disorders, and aging. PhysioToolkit is a library of open-source software for physiological signal processing and analysis, the detection of physiologically significant events using both classic techniques and novel methods based on statistical physics and nonlinear dynamics, the interactive display and characterization of signals, the creation of new databases, the simulation of physiological and other signals, the quantitative evaluation and comparison of analysis methods, and the analysis of nonstationary processes. PhysioNet is an on-line forum for the dissemination and exchange of recorded biomedical signals and open-source software for analyzing them. It provides facilities for the cooperative analysis of data and the evaluation of proposed new algorithms. In addition to providing free electronic access to PhysioBank data and PhysioToolkit software via the World Wide Web (http://www.physionet. org), PhysioNet offers services and training via on-line tutorials to assist users with varying levels of expertise.

Databases as Topic↗
PubMed2000

Neutrophilia and congestive heart failure after acute myocardial infarction.

BACKGROUND: Inflammation associated with acute myocardial infarction (AMI) is frequently marked by a peripheral leukocytosis and relative neutrophilia. Whether this process may contribute to the development of postinfarction congestive heart failure (CHF) is not established. The objective of this study was to examine the association between hospital admission peripheral total leukocyte count and the neutrophil percentage and the subsequent development of CHF in patients with AMI. The study was designed as a retrospective cohort study in the setting of a tertiary referral hospital. Participants included 185 patients discharged with a diagnosis of AMI between May 1 and Sept 30, 1996. METHODS AND RESULTS: Outcome measures included clinical episodes of CHF with confirmatory chest roentgenogram findings and/or echocardiographic evidence of contractile dysfunction. Multivariable logistic regression analyses were performed to examine the relation between the total leukocyte count, neutrophil percentage, and the development of CHF in the first 4 days after AMI while controlling for baseline characteristics and early therapeutic interventions. Thirty-one percent of the cohort had a leukocyte count >11.0 x10(9)/L on admission to the hospital; 65% had a neutrophil percentage >65%, and 61% had a lymphocyte percentage </=25%. CHF developed in 43% of the cohort. Of these, 92. 5% had relative neutrophilia (neutrophil percentage >65%) compared with 45% of those in whom CHF did not develop. Multivariable analysis revealed a highly significant association between relative neutrophilia and the subsequent development of CHF (odds ratio 14.3; 95% confidence interval 5.2 to 39.3). CONCLUSIONS: Relative neutrophilia on admission to the hospital in patients with AMI is significantly associated with the early development of CHF. This association may help in the identification of individuals at high risk who might benefit from more aggressive interventions to prevent or reduce the risk of CHF.

Adult↗
PubMed2000

One-year follow-up of medication management capacity in highly functioning older adults.

BACKGROUND: We tested the hypothesis that impairment in the ability to take medication independently predicts early functional decline. METHODS: A 12-month, prospective cohort study was performed at two continuing-care retirement facilities using the Drug Regimen Unassisted Grading Scale (DRUGS). This geriatric screening tool utilizes a stepwise progression of four tasks: (i) identification, (ii) access. (iii) dosage, and (iv) timing. RESULTS: Forty-seven (86%) of the eligible participants completed the 12-month follow-up assessment; three were transferred to skilled nursing facilities. The mean age at study entry was 84.2+/-5.1 years; 72% of the participants were women, and 68% were college educated. At 12 months there was a decline in the Mini-Mental State Examination (MMSE) score (p = .029), an increase in the timed "Up and Go" test (p = .023), and a decline in the DRUGS score (p .029). Nine (18%) of the participants resided in assisted- versus independent-living situations compared with three participants (5%) at study entry (p = .031). Both 12-month DRUGS score and 12-month self-reported medication management capacity were associated with 12-month MMSE (p = .0001 and p = .019, respectively). Baseline DRUGS score was associated with 12-month MMSE and Geriatric Depression Scale scores (p = .0002 and p = .002, respectively). Both baseline DRUGS score and self-reported medication management capacity were also associated with residence in assisted-living communities at 6 months (p = .029 and p = .040, respectively). MMSE was not associated with any of the clinical outcomes.

Activities of Daily Living↗
PubMed2000

Association of muscle power with functional status in community-dwelling elderly women.

BACKGROUND: Identification of the physiologic factors most relevant to functional independence in the elderly population is critical for the design of effective interventions. It has been suggested that muscle power may be more directly related to impaired physical performance than muscle strength in elderly persons. We tested the hypothesis that peak muscle power is closely associated with self-reported functional status in sedentary elderly community-dwelling women. METHODS: We used baseline data that were collected as part of a 1-year randomized controlled clinical trial of a combined program of strength, power, and endurance training in 80 elderly women (mean age 74.8 +/- 5.0 years) with 3.2 +/- 1.9 chronic diseases, selected for baseline functional impairment and/or falls. RESULTS: Functional status at baseline was related in univariate analyses to physiologic capacity, habitual physical activity level, neuropsychological status, and medical diagnoses. Leg power had the strongest univariate correlation to self-reported functional status (r = -.47, p < .0001) of any of the physiologic factors we tested. In a forward stepwise regression model, leg press power and habitual physical activity level were the only two factors that contributed independently to functional status (r = .64, p < .0001), accounting for 40% of the variance in functional status. CONCLUSIONS: Leg power is a strong predictor of self-reported functional status in elderly women.

Activities of Daily Living↗