Background: slower gait in older adults is related to smaller volume of the prefrontal area (PFAv). The pathways underlying this association have not yet been explored. Understanding slowing gait could help improve function in older age. We examine whether the association between smaller PFAv and slower gait is explained by lower performance on numerous neuropsychological tests.

Hypothesis: we hypothesise that slower information processing explains this association, while tests of language or memory will not.

Methods: data on brain imaging, neuropsychological tests (information processing speed, visuospatial attention, memory, language, mood) and time to walk 15 feet were obtained in 214 adults (73.3 years, 62% women) free from stroke and dementia. Covariates included central (white matter hyperintensities, vision) and peripheral contributors of gait (vibration sense, muscle strength, arthritis, body mass index), demographics (age, race, gender, education), as well as markers of prevalent vascular diseases (cardiovascular disease, diabetes and ankle arm index).

Results: in linear regression models, smaller PFAv was associated with slower time to walk independent of covariates. This association was no longer significant after adding information processing speed to the model. None of the other neuropsychological tests significantly attenuated this association.

Conclusions: we conclude that smaller PFAv may contribute to slower gait through slower information processing. Future longitudinal studies are warranted to examine the casual relationship between focal brain atrophy with slowing in information processing and gait.

OBJECTIVES

While gait speed (GS) predicts many outcomes in older adults, Timed Up and Go (TUG) is recommended for clinical assessment of mobility and fall risk. The two measures are rarely compared. We assessed whether TUG is superior to GS in predicting multiple geriatric outcomes.

DESIGN

Prospective cohort study.

SETTING

Medicare health maintenance organization and Veterans’ Affairs primary care clinics.

PARTICIPANTS

Adults aged 65 years and older (N = 457).

MEASUREMENTS

Baseline GS and TUG were used to predict health decline by EuroQol and SF-36 global health; functional decline by NHIS ADL score and SF-36 physical function index; hospitalization; and single and recurrent falls over 1 year.

RESULTS

Mean age was 74 years and 44% were female. Odds ratios for all outcomes were equivalent for GS and TUG. Using area under the ROC curve ≥ 0.7 for acceptable predictive ability, GS and TUG each alone predicted decline in global health, new ADL difficulty, and falls, with no difference in predictive ability between performance measures. Neither performance measure predicted hospitalization, EuroQol decline, or physical function decline. As continuous variables, TUG did not add predictive ability to GS for any outcome.

CONCLUSION

GS predicts most geriatric outcomes, including falls, as does the TUG. The time alone in TUG may not add to information provided by GS, although its qualitative elements may have other utility.

Objective

To examine the prevalence and correlates of non-opioid and opioid analgesic use and descriptively evaluate potential undertreatment in a sample of community-dwelling elders with symptomatic knee and/or hip osteoarthritis (OA).

Design

Cross-sectional

Setting

Health, Aging and Body Composition Study

Patients

652 participants attending the year 6 visit (2002-03) with symptomatic knee and/or hip OA.

Outcome Measures

Analgesic use was defined as taking ≥ 1 non-opioid and/or ≥ 1 opioid receptor agonist. Non-opioid and opioid doses were standardized across all agents by dividing the daily dose used by the minimum effective analgesic daily dose. Inadequate pain control was defined as severe/extreme OA pain in the past 30 days from a modified Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC).

Results

Just over half (51.4%) reported taking at least one non-opioid analgesic and approximately 10% were taking an opioid, most (88.5%) of whom also took a non-opioid. One in five participants (19.3%) had inadequate pain control, 39% of whom were using < 1 standardized daily dose of either a non-opioid or opioid analgesic. In adjusted analyses, severe/extreme OA pain was significantly associated with both non-opioid (adjusted odds ratio [AOR]=2.44; 95% confidence interval [95% CI]=1.49-3.99) and opioid (AOR=2.64; 95% CI, 1.26-5.53) use.

Conclusions

Although older adults with severe/extreme knee and/or hip OA pain are more likely to take analgesics than those with less severe pain, a sizable proportion take less than therapeutic doses and thus may be undertreated. Further research is needed to examine barriers to optimal analgesic use.

Background.

Striatal dopamine activity declines with normal aging. Age-related striatal dopaminergic denervation (SDD) has been implicated in standing balance and unperturbed gait. The goal of this study was to analyze the association between the degree of SDD and the magnitude of an unexpected slip perturbation induced during gait.

Methods.

Fifty healthy participants aged 20–86 years old underwent dopamine transporter positron emission tomography to classify SDD severity as mild, moderate, or severe. Participants also walked on a floor that was unexpectedly contaminated with a glycerol solution for gait testing. The magnitude of a slip was quantified using the peak slip velocity (PSV), measured at the slipping foot. Data were analyzed for both fast (greater than 1.2 m/s) and slow walkers as gait speed correlated with slip severity. All data analyses were age adjusted.

Results.

Greater severity of dopaminergic denervation in the caudate nucleus was correlated with higher PSV (p < .01) but only in the fast speed walking group. The relationship between SDD in the putamen and slip severity was not statistically significant in fast and slow walkers.

Conclusions.

Age-related SDD may impact the ability to recover from large perturbations during walking in individuals who typically walk fast. This effect, prominent in the caudate nucleus, may implicate a role of cognitive frontostriatal pathways in the executive control of gait when balance is challenged by large perturbations. Finally, a cautious gait behavior present in slow walkers may explain the apparent lack of involvement of striatal dopaminergic pathways in postural responses to slips.

Motor abundance allows individuals to perform any task reliably while being variable in movement's particulars. The study investigated age-related differences in this feature when young adults (YA) and older adults (OA) performed challenging tasks, namely treadmill walking alone and while performing a cognitive task. A goal function for treadmill walking was first defined, i.e., maintain constant speed at each step, which led to a goal equivalent manifold (GEM) containing all combinations of step time and step length that equally satisfied the function. Given the GEM, amounts of goal-equivalent and non-goal-equivalent variability were afterwards determined and used to define an index providing information about the set of effective motor solutions relative to the GEM. The set was limited in OA compared to YA in treadmill walking alone, indicating that OA made less flexible use of motor abundance than YA. However, this differentiation between YA and OA disappeared when concurrently performing the cognitive task. It is proposed that OA might have benefited from cognitive compensation.

Objective

Angiotensin-converting enzyme (ACE) inhibitors and statin medications have been proposed as potential agents to prevent or delay physical disability; yet limited research has evaluated whether such use in older community dwelling adults is associated with a lower risk of incident mobility limitation.

Design

Longitudinal cohort study

Setting

Health, Aging and Body Composition (Health ABC)

Participants

3055 participants who were well functioning at baseline (e.g., no mobility limitations).

Measurements

Summated standardized daily doses (low, medium and high) and duration of ACE inhibitor and statin use was computed. Mobility limitation (two consecutive self-reports of having any difficulty walking 1/4 mile or climbing 10 steps without resting) was assessed every 6 months after baseline. Multivariable Cox proportional hazard analyses were conducted adjusting for demographics, health status, and health behaviors.

Results

At baseline, ACE inhibitors and statins were used by 15.2% and 12.9%, respectively and both increased to over 25% by year 6. Over 6.5 years of follow-up, 49.8% had developed mobility limitation. In separate multivariable models, neither ACE inhibitor (multivariate hazard ratio [HR] 0.95; 95% confidence interval [CI] 0.82–1.09) nor statin use (multivariate HR 1.02; 95% CI 0.87–1.17) was associated with a lower risk for mobility limitation. Similar findings were seen in analyses examining dose- and duration-response relationships and sensitivity analyses restricted to those with hypertension.

Conclusions

These findings indicate that ACE inhibitors and statins widely prescribed to treat hypertension and hypercholesterolemia, respectively do not lower risk of mobility limitation, an important life quality indicator.

Background

Physical exercise has the potential to affect cognitive function, but most evidence to date focuses on cognitive effects of fitness training. Cognitive exercise also may influence cognitive function, but many cognitive training paradigms have failed to provide carry-over to daily cognitive function. Video games provide a broader, more contextual approach to cognitive training that may induce cognitive gains and have carry over to daily function. Most video games do not involve physical exercise, but some novel forms of interactive video games combine physical activity and cognitive challenge.

Methods/Design

This paper describes a randomized clinical trial in 168 postmenopausal sedentary overweight women that compares an interactive video dance game with brisk walking and delayed entry controls. The primary endpoint is adherence to activity at six months. Additional endpoints include aspects of physical and mental health. We focus this report primarily on the rationale and plans for assessment of multiple cognitive functions.

Discussion

This randomized clinical trial may provide new information about the cognitive effects of interactive videodance. It is also the first trial to examine physical and cognitive effects in older women. Interactive video games may offer novel strategies to promote physical activity and health across the life span.

The study is IRB approved and the number is: PRO08080012

ClinicalTrials.gov Identifier: NCT01443455

Background

Arousal symptoms (e.g., sleepiness) are common in Parkinson disease and pupillary unrest (spontaneous changes in pupil diameter) is positively associated with sleepiness. We explored pupillary unrest in Parkinson disease.

Methods

Arousal symptoms (Epworth sleepiness scale and sleep/fatigue domain of the non-motor symptoms scale for Parkinson disease (NMS-sleep)) and pupillary unrest were assessed in 31 participants (14 PD, 17 controls). Effect sizes and t-tests compared Parkinson disease with control participants. Correlation coefficients were calculated among arousal symptoms, pupillary unrest and UPDRS-III. Linear regression was performed with arousal symptoms or pupillary unrest as outcome.

Results

Parkinson disease participants reported more arousal symptoms than controls. Pupillary unrest, arousal symptoms and UPDRS-III were positively correlated. The association between NMS-sleep score and pupillary unrest was higher in Parkinson disease versus controls, and higher in those with more Parkinsonian motor signs. UPRDS-III was positively associated with pupillary unrest.

Conclusions

Pupillary unrest correlates with motor and non-motor features associated with Lewy-related pathology, suggesting it may be a non-motor marker of progression in Parkinson disease.

ABSTRACT

Background

Mobility, such as walking 1/4 mile, is a valuable but underutilized health indicator among older adults. For mobility to be successfully integrated into clinical practice and health policy, an easily assessed marker that predicts subsequent health outcomes is required.

Objective

To determine the association between mobility, defined as self-reported ability to walk 1/4 mile, and mortality, functional decline, and health care utilization and costs during the subsequent year.

Design

Analysis of longitudinal data from the 2003–2004 Medicare Current Beneficiary Survey, a nationally representative sample of Medicare beneficiaries.

Participants

Participants comprised 5895 community-dwelling adults aged 65 years or older enrolled in Medicare.

Main Measures

Mobility (self-reported ability to walk 1/4 mile), mortality, incident difficulty with activities of daily living (ADLs), total annual health care costs, and hospitalization rates.

Key Results

Among older adults, 28% reported difficulty and 17% inability to walk 1/4 mile at baseline. Compared to those without difficulty and adjusting for demographics, socioeconomic status, chronic conditions, and health behaviors, mortality was greater in those with difficulty [AOR (95% CI): 1.57 (1.10-2.24)] and inability [AOR (CI): 2.73 (1.79-4.15)]. New functional disability also occurred more frequently as self-reported ability to walk 1/4 mile declined (subsequent incident disability among those with no difficulty, difficulty, or inability to walk 1/4 mile at baseline was 11%, 29%, and 47% for instrumental ADLs, and 4%, 14%, and 23% for basic ADLs). Total annual health care costs were $2773 higher (95% CI $1443-4102) in persons with difficulty and $3919 higher (CI $1948-5890) in those who were unable. For each 100 persons, older adults reporting difficulty walking 1/4 mile at baseline experienced an additional 14 hospitalizations (95% CI 8-20), and those who were unable experienced an additional 22 hospitalizations (CI 14-30) during the follow-up period, compared to persons without walking difficulty.

Conclusions

Mobility disability, a simple self-report measure, is a powerful predictor of future health, function, and utilization independent of usual health and demographic indicators. Mobility disability may be used to target high-risk patients for care management and preventive interventions.

Background

In Parkinson's disease (PD), neurodegenerative changes have been observed in autonomic pathways involving multiple organ systems. We explore pupillary and cardiac autonomic measures as physiological manifestations of PD neurodegeneration.

Methods

Pupil measures (pupillary unrest (spontaneous changes of pupil diameter in darkness), constriction velocity and redilation velocity) were assessed in 35 participants (17 PD, 18 controls). Simultaneous cardiac measures (respiratory sinus arrythmia during deep breathing, Valsalva ratio, resting heart rate variability (HRV), orthostatic change in blood pressure and orthostatic change in heart rate) were obtained. Nonparametric statistics were used to compare PD with control participants and to calculate correlation coefficients between pupillary and cardiac measures.

Results

Pupillary unrest and orthostatic decreases in systolic blood pressure were greater in PD than controls. Respiratory sinus arrythmia during deep breathing and resting HRV were lower in PD. Among all participants, there was a negative correlation between HRV and redilation velocity and a positive correlation between orthostatic change in heart rate and pupillary unrest. A modifying effect of PD was found on the association between high frequency HRV and pupillary unrest.

Conclusions

Results demonstrate simultaneous autonomic dysfunction in both pupillary and cardiac systems in PD. The correlations between pupillary and cardiac measures suggest shared central centers of autonomic integration, while the modifying effect of PD may reflect autonomic effects of PD-related pathology not present in controls.

Successful aging is a multidimensional construct that could be viewed as a continuum of achievement. Based on the disability model proposed by the WHO International Classification of Functioning, Disability and Health, successful aging includes not only the presence or absence of disease, but also aspects of mobility and social participation. Here we review definitions of successful aging and discuss relevance of the disability model in the evaluation of successful aging and frailty. In particular, we summarize evidences that highlight the importance of measures of mobility (ability to walk and perform activities of daily living), and social participation in identifying and locating older adults across the range of the successful aging continuum. Lastly, we discuss the role of inflammation in age-related decline and in frailty. Future research directions are proposed, including identifying causal pathways among inflammatory markers, disability, and frailty. A better understanding of immunological functioning in late life may help unlock novel ways to promote successful aging.

Background.

Altered biomechanics and/or neural control disrupt the timing of postures and muscle patterns necessary for smooth and regular stepping. Harmonic ratio of trunk accelerations has been proposed as a measure of smoothness of walking. We sought to validate this measure of smoothness by examining the measure in groups expected to differ in smoothness (ie, young and old) and across walking conditions expected to affect smoothness (ie, straight path, curved path, and dual task).

Methods.

Thirty young (mean age = 24.4 ± 4.3 years) and 30 older adults (mean age = 77.5 ± 5.1 years) who could ambulate independently participated. We measured linear acceleration of the body along vertical, anterior-posterior, and medial–lateral axes using a triaxial accelerometer firmly attached to the skin over the L3 segment of the lumbar spine during straight path, curved path, and dual task (reciting every other letter of the alphabet) walking.

Results.

Older adults had lower harmonic ratio anterior-posterior (HRAP), that is, were less smooth in the direction of motion and walked more slowly than young adults for all walking conditions. Once the analyses were adjusted for walking speed, only HRAP differed between young and old participants for all walking conditions. For the most part, both young and old participants were less smooth for slow pace walking, curved path walking, and dual task walking compared with usual pace straight path walking.

Conclusions.

The harmonic ratio, calculated from trunk acceleration, is a valid measure of smoothness of walking, which may be thought of as a measure of the motor control of walking.

Background.

Short-term adherence to physical activity (PA) in older adults improves psychomotor processing abilities and is associated with greater brain activation. It is not known whether these associations are also significant for longer-term adherence to moderate-intensity activities.

Methods.

We measured the cross-sectional association of regular walking with brain activation while performing the digit symbol substitution test (DSST). Participants of the lifestyle interventions and independence for elders—pilot study were examined 2 years after completing a 1-year treatment, consisting of either PA or education in successful aging (SA). Data were obtained from 20 PA participants who reported having remained active for 2 years after the end of the treatment and from 10 SA participants who reported having remained sedentary during the same period (mean age: 81.5 and 80.8 years). Complete brain activation and behavioral data were available for 17 PA and 10 SA participants.

Results.

Two years after the formal intervention had ended, the PA group engaged in more minutes of moderate activity and had significantly greater DSST score and higher brain activation within regions important for processing speed (left dorsolateral prefrontal, posterior parietal, and anterior cingulate cortices). Associations were independent of self-reported health, blood pressure, cognition, medication records, gray matter atrophy, and white matter hyperintensities.

Conclusions.

Persistent engagement in PA may have beneficial effects on psychomotor processing speed and brain activation, even for moderate levels and even when started late in life. Future studies are warranted to assess whether these beneficial effects are explained by delayed neuronal degeneration and/or new neurogenesis.

Context

While fatigue is a common and distressing symptom, a well-specified definition of fatigue is lacking. One of the least well-defined aspects of fatigue is its quality, which might reflect the underlying pathophysiology.

Objectives

To identify qualities of fatigue and assess whether they are associated with distinct chronic conditions.

Methods

We identified five fatigue qualities in the literature, two mental and three physical, and selected representative items from those available in our data from a prospective cohort of 495 community-dwelling primary care patients aged 65 years or older. We then examined the prevalence of each quality, the correlations among qualities, and the association of fatigue qualities with health and functional status, including chronic conditions.

Results

Fatigue was very common among older primary care patients, with 70% reporting any fatigue and 43% reporting feeling tired most of the time, and was associated with worse health and functional status. Physical fatigue qualities were more common than mental qualities. Correlations among fatigue qualities were 0.09–0.27 and did not support the mental versus physical classification. Different fatigue qualities were not well explained by older adults’ underlying chronic conditions. Rather the cumulative number of fatigue qualities was associated with worse health and function.

Conclusion

These first steps in exploring fatigue qualities suggest that different fatigue qualities could represent disparate manifestations of a common underlying etiology, while not ruling out distinct underlying pathophysiologies.

Most aging patients have multiple concurrent health problems. However, most current medical practice and research are largely based on a single disease model, failing to account for the simultaneous presence of multiple conditions. Clinical trials, practice guidelines, and pay-for-performance schemes may thus have limited applicability in older patients. We report on the 2005 American Geriatrics Society/National Institute on Aging conference on Comorbid Disease and Multiple Morbidity in an Aging Society. The two-day conference was designed to clarify concepts of multiple concurrent health conditions; explore implications for causation, health, function and systems of care; identify important gaps in knowledge; and propose useful next steps. While the conference did not attempt to standardize terminology, we here develop the concepts of comorbidity, multiple morbidity, condition clusters, physiological health, and overall health as they were used. The present report also summarizes sessions addressing the societal burden of comorbidity, and clinical research on particular diseases within the framework of comorbidity concepts. Next steps recommended include continuing clarification of terms and conceptual approaches, consideration of developing and improving measures, as well as developing new research directions.

OBJECTIVES

To assess the predictive value of five performance-based measures for the onset of difficulty in basic activities of daily living (ADL).

DESIGN

A prospective cohort study; home visits every 6 months for 18 months.

SETTING

Community-based

PARTICIPANTS

Community-dwelling older adults, n=110, (mean age, 80; SD, 7.0; range, 67-98 years) who reported no difficulty in basic ADLs.

MEASUREMENTS

The Short Physical Performance Battery (SPPB), gait speed, Berg Balance Scale (BBS), grip strength, and Timed Up & Go Test (TUG) were evaluated at baseline. Seven ADL items were assessed at baseline, 6, 12 and 18 months. The onset of basic ADL disability was self-report of difficulty in any of the 7 ADL items. Logistic regression models were fitted for each of the physical performance measures to predict onset of basic ADL difficulty at 6, 12, and 18 months.

RESULTS

After controlling for age, co-morbid conditions, and gender, the BBS was the most consistent and best predictor for the onset of basic ADL difficulty over an 18-month period (6 months, c-statistic=.725 (.60, .85); 12 months, c-statistic=.840 (.75, .93); 18 months, c-statistic=.821 (.71, .93)). The SPPB showed excellent predictive value for the onset of difficulty at 12 months. The number of older adults completed the 6, 12, and 18-month follow-up visits were 95, 89, and 75, respectively.

CONCLUSION

BBS, followed by SPPB, TUG, gait speed and grip strength were predictive for the onset of basic ADL difficulty over an 18-month period in community-dwelling older adults. Screening nondisabled older adults with simple performance tests could allow clinicians to identify those at risk for ADL difficulty, and may help to detect early functional decline.

Context

Survival estimates help individualize goals of care for geriatric patients, but life tables fail to account for the great variability in survival. Physical performance measures, such as gait speed, might help account for variability, allowing clinicians to make more individualized estimates.

Objective

To evaluate the relationship between gait speed and survival.

Design, Setting, and Participants

Pooled analysis of 9 cohort studies (collected between 1986 and 2000), using individual data from 34 485 community-dwelling older adults aged 65 years or older with baseline gait speed data, followed up for 6 to 21 years. Participants were a mean (SD) age of 73.5 (5.9) years; 59.6%, women; and 79.8%, white; and had a mean (SD) gait speed of 0.92 (0.27) m/s.

Main Outcome Measures

Survival rates and life expectancy.

Results

There were 17 528 deaths; the overall 5-year survival rate was 84.8% (confidence interval [CI], 79.6%–88.8%)and 10-year survival rate was 59.7% (95%CI, 46.5%–70.6%). Gait speed was associated with survival in all studies (pooled hazard ratio per 0.1 m/s, 0.88; 95% CI, 0.87–0.90; P<. 001). Survival increased across the full range of gait speeds, with significant increments per 0.1 m/s. At age 75, predicted 10-year survival across the range of gait speeds ranged from 19% to 87% in men and from 35% to 91% in women. Predicted survival based on age, sex, and gait speed was as accurate as predicted based on age, sex, use of mobility aids, and self-reported function or as age, sex, chronic conditions, smoking history, blood pressure, body mass index, and hospitalization.

Conclusion

In this pooled analysis of individual data from 9 selected cohorts, gait speed was associated with survival in older adults.

Objectives

To establish nationally representative estimates of the prevalence of self-reported difficulty and inability to walk ¼ mile among older adults and to identify the characteristics independently associated with difficulty or inability to walk ¼ mile.

Design

Cross-sectional analysis of data from the 2003 Cost and Use Medicare Current Beneficiary Survey.

Setting

Community.

Participants

9563 community-dwelling Medicare beneficiaries aged 65 years or older, representing an estimated total population of 34.2 million older adults.

Measurements

Self-reported ability to walk ¼ mile, sociodemographics, chronic conditions, body mass index, smoking, and functional status.

Results

In 2003, an estimated 9.5 million aged Medicare beneficiaries had difficulty walking ¼ mile and 5.9 million were unable. Among the 20.2 million older adults with no difficulty in basic or instrumental activities of daily living (ADL), an estimated 4.3 million (21%) had limited ability to walk ¼ mile. Having difficulty or being unable to walk ¼ mile was independently associated with older age, female sex, non-Hispanic ethnicity, lower educational level, Medicaid entitlement, most chronic medical conditions, current smoking, and being overweight or obese.

Conclusion

Almost half of older adults, and 20% of those reporting no ADL limitations, report limited ability to walk ¼ mile. Among functionally independent older adults, reported ability to walk ¼ mile can identify vulnerable older adults with greater medical problems and fewer resources, and may be a valuable clinical marker in planning their care. Future work is needed to determine the association between ¼ mile walk ability and subsequent functional decline and healthcare utilization.

Context

Older adults responding to executive control function (ECF) tasks show greater brain activation on functional MRI (fMRI). It is not clear whether greater fMRI activation indicates a strategy to compensate for underlying brain structural abnormalities while maintaining higher performance.

Objective

To identify the patterns of fMRI activation in relationship with ECF performance and with brain structural abnormalities.

Design

Cross-sectional analysis. Main variables of interest: fMRI activation, accuracy while performing an ECF task (Digit Symbol Substitution Test), volume of white matter hyperintensities and of total brain atrophy.

Setting

Cohort of community-dwelling older adults.

Participants

Data were obtained on 25 older adults (20 women, 81 years mean age).

Outcome Measure

Accuracy (number of correct response / total number of responses) while performing the Digit Symbol Substitution Test.

Results

Greater accuracy was significantly associated with greater peak fMRI activation, from ECF regions, including left middle frontal gyrus and right posterior parietal cortex. Greater WMH was associated with lower activation within accuracy-related regions. The interaction of accuracy by white matter hyperintensities volume was significant within the left posterior parietal region. Specifically, the correlation of white matter hyperintensities volume with fMRI activation varied as a function of accuracy and it was positive for greater accuracy. Associations with brain atrophy were not significant.

Conclusions

Recruitment of additional areas and overall greater brain activation in older adults is associated with higher performance. Posterior parietal activation may be particularly important to maintain higher accuracy in the presence of underlying brain connectivity structural abnormalities.

Objectives

Gait variability is an important indicator of impaired mobility in older adults; however, little is known about the meaning of change in gait variability over time. This study estimated clinically meaningful change in measures of gait variability using both distribution-and anchor-based approaches.

Design

Community-based observational cohort study.

Setting

Bronx County and the research center at Albert Einstein College of Medicine.

Participants

Of 1148 participants in the Einstein Aging Study, 241 had quantitative gait assessments in two consecutive years between 2001 and 2005.

Measurements

Gait variables were collected using a 12-foot instrumented walkway as participants walked at their normal walking speed. Gait variability was defined as the within-person standard deviation (SD) across steps in two 12-foot walks. Distribution-based meaningful change estimates used Cohen’s effect size (0.2 for small and 0.5 for moderate effects). Anchor-based estimates were obtained using dichotomous and ordinal self-reported walking ability ratings as anchors.

Results

Distribution based estimates for small and substantial changes of variability measures were: stance time 0.005 and 0.014 s; swing time 0.003 and 0.009 s; step length 0.24 and 0.61 cm; and step width 0.03 and 0.08 cm. Among those reporting no change in walking ability, measures of gait variability were stable over one year. Among those reporting a decline in walking, stance time and swing time variability increased. Among those reporting an improvement in walking, only step length variability improved.

Conclusion

Preliminary criteria for meaningful change are 0.01 s for stance time and swing time variability and 0.25 cm for step length variability. These estimates may identify important changes over time in both clinical settings and research studies.

Background

Therapeutic activities to improve mobility often include walking practice and exercises to improve deficits in endurance, strength, and balance. Because walking may also be energy inefficient in people with decreased mobility, another approach is to reduce energy cost by improving timing and coordination (TC) of movement.

Methods

This pilot randomized trial of older adults with slow and variable gait offered two types of therapeutic activity over 12 weeks. One addressed Walking, Endurance, Balance, and Strength (WEBS) and the other focused on TC. Outcomes were energy cost of walking and measures of mobility.

Results

Of 50 participants (mean age, 77.2 ± 5.5 years, 65% women), 47 completed the study. Baseline gait speed was 0.85 ± 0.13 m/s and energy cost of walking was 0.30 ± 0.10 mL/kg/m, nearly twice normal. Both interventions increased gait speed (TC by 0.21 m/s and WEBS by 0.14 m/s, p < .001). TC reduced the energy cost of walking 0.10 ± 0.03 mL/kg/m more than WEBS (p < .001) and reduced the modified Gait Abnormalities Rating Scale 1.5 ± 0.6 more points than WEBS (p < .05). TC had a 9.8 ± 3.5 points greater gain than WEBS in self-reported confidence in walking (p < .01).

Conclusions

In older adults with slow and variable gait, activity focused on TC reduced the energy cost of walking and improved confidence in walking more than WEBS while generating at least equivalent gains in mobility. To optimize mobility, future larger studies should assess various combinations of TC and WEBS over longer periods of time.

Background

The late life disability instrument (LLDI) was developed to assess limitations in instrumental and management roles using a small and restricted sample. In this paper we examine the measurement properties of the LLDI using data from the Lifestyle Interventions and Independence for Elders Pilot (LIFE-P) study.

Methods

LIFE-P participants, aged 70-89 years, were at elevated risk of disability. The 424 participants were enrolled at the Cooper Institute, Stanford University, University of Pittsburgh, and Wake Forest University. Physical activity and successful aging health education interventions were compared after 12-months of follow-up. Using factor analysis, we determined whether the LLDI's factor structure was comparable with that reported previously. We further examined how each item related to measured disability using item response theory (IRT).

Results

The factor structure for the limitation domain within the LLDI in the LIFE-P study did not corroborate previous findings. However, the factor structure using the abbreviated version was supported. Social and personal role factors were identified. IRT analysis revealed that each item in the social role factor provided a similar level of information, whereas the items in the personal role factor tended to provide different levels of information.

Conclusions

Within the context of community-based clinical intervention research in aged populations, an abbreviated version of the LLDI performed better than the full 16-item version. In addition, the personal subscale would benefit from additional research using IRT.

Trial registration

The protocol of LIFE-P is consistent with the principles of the Declaration of Helsinki and is registered at http://www.ClinicalTrials.gov (registration # NCT00116194).