Sensory and motor peripheral nerve function and incident mobility disability

Association Between Multisensory Impairment and Depression Among Older Adults: A Population-Based Analysis

OBJECTIVE

In this study, we examine how impairments in vision, hearing, touch, and olfaction relate to depression in older adults, considering both individual and multisensory impairments (MSIs).

STUDY DESIGN

Analysis of cross-sectional data from a longitudinal investigation involving black and white older adults aged 70 to 79 at enrollment.

SETTING

We studied 1640 black and white participants in the Health ABC study using complete sensory evaluation data from years 3 to 5.

METHODS

Our MSI assessment utilized data obtained for visual acuity, hearing perception, olfactory performance, and tactile function. We performed multivariable logistic regression analyses to examine the associations between the presence of individual and MSIs and depression which was defined as the presence of antidepressants prescribed for depression, or a Center for Epidemiological Studies Depression Scale score of greater than 10.

RESULTS

We observed a possible dose-response relationship between the number of sensory impairments and depression. In adjusted models, when compared to no impairments, vision (odds ratio [OR] = 1.45, 95% confidence interval [CI]: 1.09-1.93) and hearing impairments (OR = 1.49, 95% CI: 1.11-1.99) were significantly associated with depression, whereas olfaction (OR = 1.11, 95% CI: 0.83-1.47) and tactile impairments (OR = 1.28, 95% CI: 0.96-1.70) were not. Participants with 3 sensory impairments had a higher rate of depression (OR = 2.05, 95% CI: 1.22-3.54) compared to those without impairments, and this risk increased further for those with 4 sensory impairments (OR = 2.95, 95% CI: 1.48-5.88).

CONCLUSION

The findings suggest that individuals with MSI represent a high-risk population for depression, warranting close monitoring to screen for depression. The study emphasizes the importance of considering multiple sensory impairments in the context of mental health and supports the early identification and monitoring of depression in this population.

Influence of transcutaneous electrical nerve stimulation on the distance walked by older adults during the 6-min test of walking endurance

The purpose of our study was to compare the influence of two types of transcutaneous electrical nerve stimulation (TENS) on the performance of older adults on the 6-min test of walking endurance and on the ability to maintain balance during upright standing. Twenty-six healthy older adults (72 ± 5.4 yrs) performed tests of motor function while TENS was applied to the tibialis anterior and rectus femoris muscles of each leg. Linear mixed models were used to compare the influence of TENS on walking distance in a 6-min test of walking endurance and on sway-area rate in tests of standing balance. There was a significant decrease in the distances walked in each minute of the 6-min walk test for both the Continuous and Burst TENS modes compared with Baseline (p < 0.01 and p < 0.001, respectively). The influence of TENS on walking distance was associated with several significant effects on the mean and coefficient of variation for stride length and stride frequency between the first and last minute of the test and between the two TENS modes and the Baseline values. In contrast, there was no significant effect of TENS on sway-area rate in any balance test, which indicates that the supplementary sensory feedback compromised walking performance of older adults but not the ability to maintain balance during upright standing.

Influence of transcutaneous electrical nerve stimulation on walking kinematics and standing balance of older adults who differ in walking speed

The purpose was to determine the impact of transcutaneous electrical nerve stimulation (TENS) on measures of walking kinematics and standing balance of healthy older adults who were stratified into two groups based on differences in the distance walked during the 6-min test of walking endurance. Regression models were developed to explain the variance in the 6-min distance and to assess the predictive power of balance metrics to categorize the 26 older adults (72 ± 5.4 yrs) as either slow or fast walkers. Walking kinematics were measured during 6- and 2-min walk tests that were performed with and without the concurrent application of TENS to the hip flexor and ankle dorsiflexor muscles. Participants walked briskly during the 6-min test and at a preferred pace during the 2-min test. The supplementary sensory stimulation provided by TENS did not alter the power of the models to explain the variance in the Baseline 6-min distance: Baseline, R² = 0.85; TENS, R² = 0.83. In contrast, TENS improved the explanatory power of the data obtained during the 2-min walk to account for the variance in the Baseline 6-min distance: no TENS, R² = 0.40; TENS, R² = 0.64. Logistic regression models based on force-plate and kinematic data obtained during the balance tasks were able to discriminate between the two groups with excellent certainty. The impact of TENS was greatest when older adults walked at a preferred speed but not when they walked at a brisk pace or performed tests of standing balance.

Associations of Lower Extremity Peripheral Nerve Impairment and Risk of Dementia in Black and White Older Adults

BACKGROUND AND OBJECTIVES

Peripheral nerve impairments and dementia are common among older adults and share risk factors. However, few studies have examined whether peripheral nerve function and dementia are associated. We evaluated whether lower extremity peripheral nerve impairments were associated with higher incidence of dementia and whether associations differed by comorbidity subgroups (diabetes, low vitamin B12, and APOE ε4 allele carriers).

METHODS

We studied Black and White Health, Aging, and Body Composition Study participants 70 to 79 years of age and without dementia at enrollment. Lower extremity sensory and motor peripheral nerve function was measured at year 4 (the analytic baseline of this study). Sensory nerve impairments were measured with monofilament (1.4 g, 10 g) and vibration threshold of the toe. Monofilament insensitivity was defined as unable to detect monofilament (3 of 4 touches), and vibration detection impairment was defined as >130 μm. Fibular motor impairments were defined as <1 mV compound motor action potential (CMAP) amplitude and slow nerve conduction velocity <40 m/s. Incident dementia over the following 11 years was determined from medical records, cognitive scores, and medications. Cox proportional hazard models adjusted for demographics and health conditions assessed associations of nerve impairments with incident dementia.

RESULTS

Among 2,174 participants (52% women, 35% Black), 45% could not detect monofilament 1.4 g, 9% could not detect monofilament 10 g, 6% could not feel vibration, 10% had low CMAP amplitude, and 24% had slow conduction velocity. Monofilament 10 g (hazard ratio [HR] 1.35, 95% CI 0.99-1.84) and vibration detection insensitivity (HR 1.73, 95% CI 1.24-2.40) were associated/borderline associated with a higher risk of dementia after covariate adjustment. Estimates were elevated but not significant for monofilament 1.4 g, CMAP amplitude, and conduction velocity (p > 0.05). Increasing number of peripheral nerve impairments was associated with higher risk of dementia in a graded fashion; for ≥3 impairments, the HR was 2.37 (95% CI 1.29-4.38). In subgroup analyses, effect estimates were generally higher among those with diabetes, low vitamin B12, and APOE ε4 allele except for vibration detection.

DISCUSSION

Peripheral nerve impairments, especially sensory, were associated with a higher risk of dementia even after adjustment for age and other health factors. These associations may represent a shared susceptibility to nervous system degeneration.

Extensor digitorum brevis bulk and associations with fibular motor nerve conduction amplitude

INTRODUCTION

Prior work demonstrates that fibular compound motor action potential (CMAP) amplitude <4.0 mV predicts impairment of ankle proprioceptive precision and increased fall risk. Extensor digitorum brevis (EDB) inspection may present a simple clinical surrogate for CMAP amplitude.

OBJECTIVE

(1) To estimate the inter-rater reliability of assessment of EDB bulk. (2) To determine whether inspection of EDB bulk is associated with fibular CMAP amplitude.

DESIGN

Prospective inter-raterreliability study.

SETTING

Academic center outpatient Physical Medicine & Rehabilitation electromyography (EMG) clinics.

PARTICIPANTS

Fifty-two adult participants (102 feet).

MAIN OUTCOME MEASURES

(1) Inter-rater reliability of assessment of EDB bulk. (2) Mean fibular CMAP amplitude. (3) A binary measure of fibular CMAP amplitude at/above or below a 4.0 mV threshold.

RESULTS

Inter-rater reliability of EDB bulk grading was moderate (kappa: 0.65 [95% confidence interval (CI) 0.48-0.82]). The mean CMAP value was 5.9 ± 2.2 mV when bulk was normal, 3.4 ± 2.1 mV when diminished, and 0.6 ± 0.9 mV when atrophied. A multivariable analysis demonstrated that EDB bulk, distal symmetric polyneuropathy (DSP), and lumbar radiculopathy were all associated with CMAP amplitude. The sensitivity and specificity of grading muscle bulk as normal versus abnormal in detecting CMAP amplitude above or below 4.0 mV were 0.86 (95% CI 0.78-0.94) and 0.71 (95% CI 0.54-0.88), respectively. An atrophied EDB was a highly specific indicator that CMAP amplitude was abnormal (<4.0 mV) in 100% of cases (8/8).

CONCLUSIONS

EDB bulk was associated with fibular CMAP amplitude. Atrophy was a highly specific indicator for CMAP amplitude below 4.0 mV. Evaluation of EDB bulk may represent a quick and easy clinical surrogate marker for CMAP amplitude and distal neuromuscular impairment.

Metabolic syndrome and the benefit of a physical activity intervention on lower-extremity function: Results from a randomized clinical trial

BACKGROUND

In older adults, increases in physical activity may prevent decline in lower-extremity function, but whether the benefit differs according to metabolic syndrome (MetS) status is uncertain. We aim to investigate whether structured physical activity is associated with less decline in lower-extremity function among older adults with versus without MetS.

METHODS

We used data from the multicenter Lifestyle Interventions and Independence for Elders (LIFE) study to analyze 1535 sedentary functionally-vulnerable women and men, aged 70 to 89 years old, assessed every 6 months (February 2010-December 2013) for an average of 2.7 years. Participants were randomized to a structured, moderate-intensity physical activity intervention (PA; n = 766) or health education program (HE; n = 769). MetS was defined according to the 2009 multi-agency harmonized criteria. Lower-extremity function was assessed by 400-m walking speed and the Short Physical Performance Battery (SPPB) score.

RESULTS

763 (49.7%) participants met criteria for MetS at baseline. Relative to HE, PA was associated with faster 400-m walking speed among participants with MetS (P < 0.001) but not among those without MetS (P = 0.91), although the test for statistical interaction was marginally non-significant (P = 0.07). In contrast, no benefit of PA versus HE was observed on the SPPB score in either MetS subgroup.

CONCLUSIONS

Among older adults at high risk for mobility disability, moderate-intensity physical activity conveys significant benefits in 400-m walking speed but not SPPB in those with, but not without, MetS. The LIFE physical activity program may be an effective strategy for maintaining or improving walking speed among vulnerable older adults with MetS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT01072500.

Association between 30-s Chair Stand-Up Test and Anthropometric Values, Vibration Perception Threshold, FHSQ, and 15-D in Patients with Type 2 Diabetes Mellitus

Simple Summary

Type 2 diabetes mellitus is a chronic global disease with a series of complications that lead to problems in the somatosensory system, the cardiovascular system, health-related quality of life, foot health, and even balance. These balance problems arise from deficits in lower limb strength, among other causes. The 30-s chair stand-up test is a test that evaluates leg strength and is an easy, quick, inexpensive, and predictive test of different parameters. How this test relates to health-related quality of life, vibration sensitivity threshold, and foot health has not been studied. This study tests the degree of the relationships of the 30-s chair stand-up test with the 15-dimensional (15-D) questionnaire, Foot Health Status Questionnaire (FHSQ), vibration sensitivity threshold, and body composition questionnaires.

Abstract

Background: Type 2 diabetes mellitus (T2DM) is a chronic, worldwide disease affecting more than 400 million people. This pathology involves several associated problems, such as diabetic neuropathy complications, obesity, and foot problems, both in terms of health and sensitivity. Objective: The objective of this study was to explore the relationships of the 30-s chair stand-up test with the Foot Health Status Questionnaire (FHSQ), the vibration perception threshold (VPT), and the 15-dimensional (15-D) questionnaire in T2DM people. Methodology: Ninety participants with T2DM were assessed in terms of fat mass percentage, VPT, foot health, health-related quality of life (HRQoL), and the 30-s chair stand-up test. Results: The 30-s chair stand-up test was found to exhibit a moderate relationship with “physical activity” (rho = 0.441; p ≤ 0.001) and “vigor” (rho = 0.443; p ≤ 0.001) from FHSQ. The 30-s chair stand-up test was also found to be weakly associated with foot pain (rho = 0.358; p = 0.001), 15-D total score (rho = 0.376; p ≤ 0.001), “sleeping” (rho = 0.371; p < 0.001), and “depression” (rho = 0.352; p = 0.001). Conclusions: The 30-s chair stand-up test is associated with “physical activity”, “vigor”, and “foot pain” from the FHSQ and the 15-D questionnaire total score and its dimensions “sleeping” and “depression” in type 2 diabetes mellitus patients. Therefore, following the results obtained, qualified clinicians can use the 30-s chair stand-up test as a good tool for monitoring and managing type 2 diabetes.

Comparison between quantitative and subjective assessments of chemotherapy-induced peripheral neuropathy in cancer patients: A prospective cohort study

OBJECTIVE

Chemotherapy-induced peripheral neuropathy (CIPN) is a common adverse event experienced by cancer patients. In general, CIPN is evaluated subjectively based on patient self-assessment or clinician-reported scales; evidence supporting the utility and validity of quantitative sensory tests (QST) is lacking in this patient population. The aim of this study was to objectively assess CIPN of lower extremities by QSTs, and to evaluate the concordance between QSTs and subjective assessments.

METHODS

In this prospective cohort study, outpatients with cancer receiving chemotherapy were recruited at a single university hospital. We assessed CIPN at the lower extremities at baseline and three months after baseline. The QSTs were performed by applying a monofilament and a tuning fork to determine touch and vibration thresholds, respectively, at the affected site. Subjective assessments were performed based on the visual analog scale (VAS) and the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) toxicity grade. Kappa coefficients were calculated to evaluate the concordance between QSTs and subjective assessments.

RESULTS

After exclusion and drop-outs during follow-up, nineteen patients were included in the analysis. The prevalence of patients with abnormal sensation was 37% based on QSTs, 32% based on the VAS, and 14% based on CTCAE grading, respectively. Kappa coefficients were 0.32 between QSTs and VAS, and 0.28 between QSTs and CTCAE.

CONCLUSIONS

The concordance rates between quantitative and subjective assessments were low. CIPN should be assessed using both quantitative and subjective assessments.

Swallowing impairment in older adults: association with sensorimotor peripheral nerve function from the Health, Aging and Body Composition study

BACKGROUND

The purpose of this study was to examine whether impairments in sensorimotor peripheral nerve function are associated with a higher likelihood of swallowing impairment in older adults.

METHODS

Health, Aging and Body Composition participants (n = 607, age = 75.8 ± 2.7 years, 55.8% women, 32.3% black) underwent peripheral nerve testing at Year 4 and 11 with swallowing difficulty assessed at Year 4 and 15. Nerve conduction amplitude and velocity were measured at the peroneal motor nerve. Sensory nerve function was assessed with the vibration detection threshold and monofilament (1.4-g/10-g) testing at the big toe. Symptoms of lower extremity peripheral neuropathy and difficulty swallowing were collected by self-report. Data analysis was performed using a hierarchical approach. Odds ratios (ORs) were estimated using non-conditional logistic regression.

RESULTS

At Year 15 108 (17.8%) participants had swallowing impairments. In fully adjusted models, the peripheral nerve impairments associated with swallowing impairment were numbness (OR 4.67; 95%CI 2.24-9.75) and poor motor nerve conduction velocity (OR 2.26; 95%CI 1.08-4.70). Other peripheral nerve impairments were not related to swallowing.

CONCLUSIONS

The association between slow motor nerve conduction velocity and numbness and a higher likelihood of swallowing difficulties a decade later in our prospective study identifies an important area for further investigation in older adults.

Chronic kidney disease as a risk factor for peripheral nerve impairment in older adults: A longitudinal analysis of Health, Aging and Body Composition (Health ABC) study

Introduction

Sensory and motor nerve deficits are prevalent in older adults and are associated with loss of functional independence. We hypothesize that chronic kidney disease predisposes to worsening sensorimotor nerve function over time.

Materials and methods

Participants were from the Health, Aging and Body Composition Study (N = 1121) with longitudinal data between 2000–01 (initial visit) and 2007–08 (follow-up visit). Only participants with non-impaired nerve function at the initial visit were included. The predictor was presence of CKD (estimated GFR ≤ 60 ml/min/1.73m²) from the 1999–2000 visit. Peripheral nerve function outcomes at 7-year follow-up were 1) Motor: “new” impairments in motor parameters (nerve conduction velocity NCV < 40 m/s or peroneal compound motor action potential < 1 mv) at follow-up, and 2) Sensory: “new” impairment defined as insensitivity to standard 10-g monofilament or light 1.4-g monofilament at the great toe and “worsening” as a change from light to standard touch insensitivity over time. The association between CKD and “new” or “worsening” peripheral nerve impairment was studied using logistic regression.

Results

The study population was 45.9% male, 34.3% Black and median age 75 y. CKD participants (15.6%) were older, more hypertensive, higher in BMI and had 2.37 (95% CI 1.30–4.34) fold higher adjusted odds of developing new motor nerve impairments in NCV. CKD was associated with a 2.02 (95% CI 1.01–4.03) fold higher odds of worsening monofilament insensitivity. CKD was not associated with development of new monofilament insensitivity.

Conclusions

Pre-existing CKD leads to new and worsening sensorimotor nerve impairments over a 7-year time period in community-dwelling older adults.

Peripheral Nerve Impairment and Recurrent Falls Among Women: Results From the Study of Women's Health Across the Nation

BACKGROUND

Falls and related injuries are important public health concerns yet underappreciated in early aging. This study examined the association of peripheral nerve impairment (PNI) with fall outcomes in early old aged women (60-72 years).

METHODS

Women (n = 1,725; mean age 65.1 ± 2.7 years) from the longitudinal cohort Study of Women's Health Across the Nation completed a PNI questionnaire on presence, frequency, and severity of symptoms, and 10- and 1.4-g monofilament testing in 2016-2017. PNI was defined as four or more self-reported symptoms or monofilament insensitivity. Recurrent falls (two or more) and recurrent fall injuries (two or more falls with one or more injuries) in the previous 12 months were assessed via questionnaire. Poisson regression was used to generate risk ratios (RRs) and corresponding 95% confidence intervals (CIs) for the fall outcomes, adjusting for covariates.

RESULTS

Approximately 12.3% of participants reported two ore more falls, 7.6% reported recurrent falls with injury, and 15.8% reported four or more PNI symptoms. Women with recurrent falls were more likely to report four or more PNI symptoms compared to women without recurrent falls (32.1% vs 13.5%; p < .001). One quarter (25.6%) of participants had four or more PNI symptoms or monofilament insensitivity; after adjusting for covariates, women with either symptoms or insensitivity were more likely to report recurrent falls compared to women with neither (RR = 1.64; 95% CI: 1.24, 2.17).

CONCLUSIONS

These findings suggest that PNI may identify those at high risk for falls, particularly among women during early late life. Neuropathy screening instruments such as symptom questionnaires or monofilament testing are easy to implement and may have utility for fall risk assessment.

Cardiometabolic risk factors as determinants of peripheral nerve function: the Maastricht Study

AIMS/HYPOTHESIS

We aimed to examine associations of cardiometabolic risk factors, and (pre)diabetes, with (sensorimotor) peripheral nerve function.

METHODS

In 2401 adults (aged 40-75 years) we previously determined fasting glucose, HbA_1c, triacylglycerol, HDL- and LDL-cholesterol, inflammation, waist circumference, blood pressure, smoking, glucose metabolism status (by OGTT) and medication use. Using nerve conduction tests, we measured compound muscle action potential, sensory nerve action potential amplitudes and nerve conduction velocities (NCVs) of the peroneal, tibial and sural nerves. In addition, we measured vibration perception threshold (VPT) of the hallux and assessed neuropathic pain using the DN4 interview. We assessed cross-sectional associations of risk factors with nerve function (using linear regression) and neuropathic pain (using logistic regression). Associations were adjusted for potential confounders and for each other risk factor. Associations from linear regression were presented as standardised regression coefficients (β) and 95% CIs in order to compare the magnitudes of observed associations between all risk factors and outcomes.

RESULTS

Hyperglycaemia (fasting glucose or HbA_1c) was associated with worse sensorimotor nerve function for all six outcome measures, with associations of strongest magnitude for motor peroneal and tibial NCV, β_{fasting glucose} = -0.17 SD (-0.21, -0.13) and β_{fasting glucose} = -0.18 SD (-0.23, -0.14), respectively. Hyperglycaemia was also associated with higher VPT and neuropathic pain. Larger waist circumference was associated with worse sural nerve function and higher VPT. Triacylglycerol, HDL- and LDL-cholesterol, and blood pressure were not associated with worse nerve function; however, antihypertensive medication usage (suggestive of history of exposure to hypertension) was associated with worse peroneal compound muscle action potential amplitude and NCV. Smoking was associated with worse nerve function, higher VPT and higher risk for neuropathic pain. Inflammation was associated with worse nerve function and higher VPT, but only in those with type 2 diabetes. Type 2 diabetes and, to a lesser extent, prediabetes (impaired fasting glucose and/or impaired glucose tolerance) were associated with worse nerve function, higher VPT and neuropathic pain (p for trend <0.01 for all outcomes).

CONCLUSIONS/INTERPRETATION

Hyperglycaemia (including the non-diabetic range) was most consistently associated with early-stage nerve damage. Nonetheless, larger waist circumference, inflammation, history of hypertension and smoking may also independently contribute to worse nerve function.

Incident dementia and faster rates of cognitive decline are associated with worse multisensory function summary scores

INTRODUCTION

We created a summary score for multiple sensory (multisensory) impairment and evaluated its association with dementia.

METHODS

We studied 1794 adults aged 70 to 79 who were dementia-free at enrollment and followed for up to 10 years in the Health, Aging, and Body Composition Study. The multisensory function score (0 to 12 points) was based on sample quartiles of objectively measured vision, hearing, smell, and touch summed overall. Risk of incident dementia and cognitive decline (measured by two cognitive tests) associated with the score were assessed in regression models adjusting for demographics and health conditions.

RESULTS

Dementia risk was 2.05 times higher (95% confidence interval [CI] 1.50-2.81) comparing "poor" to "good" multisensory score tertiles and 1.45 times higher comparing the "middle" to "good" tertiles (95% CI 1.09-1.91). Each point worse in the multisensory function score was associated with faster rates of cognitive decline (P < .05).

CONCLUSIONS

Worsening multisensory function, even at mild levels, was associated with accelerated cognitive aging.

Interrelated Neuromuscular and Clinical Risk Factors That Contribute to Falls

BACKGROUND

Neuromuscular and clinical factors contribute to falls among older adults, yet the interrelated nature of these factors is not well understood. We investigated the relationships between these factors and how they contribute to falls, which may help optimize fall risk assessment and prevention.

METHODS

A total of 365 primary care patients (age = 77 ± 7, 67% female) were included from the Boston Rehabilitative Impairment Study of the Elderly. Neuromuscular measures included leg strength and leg velocity, trunk extensor endurance, and knee range of motion. Clinical measures included memory, executive function, depressive symptoms, pain, sensory loss, vision, comorbidity, physical activity, mobility self-efficacy, and psychiatric medication. Factor analysis was used to evaluate clustering of factors. Negative binomial regression assessed the relationship of factors with three-year fall rate. Interactions were tested to examine whether clinical factors modified the relationship between neuromuscular factors and falls.

RESULTS

Three factors emerged: (i) neuromuscular factors, pain, and self-efficacy; (ii) memory; and (iii) executive function. Having three neuromuscular impairments predicted higher fall rate (incidence rate ratio [95% confidence interval]: 3.39 [1.82-6.32]) but was attenuated by memory (1.69 [1.10-2.61]), mobility self-efficacy (0.99 [0.98-0.99]), psychiatric medication use (1.54 [1.10-2.14]), and pain (1.13 [1.04-1.23]). Pain modified the relationship between neuromuscular impairment burden (number of neuromuscular impairments) and falls. Having three neuromuscular impairments was associated with a higher fall rate in patients with high levels of pain (5.73 [2.46-13.34]) but not among those with low pain.

CONCLUSIONS

Neuromuscular impairment burden was strongly associated with fall rate in older adults with pain. These factors should be considered together during fall risk assessment, post fall assessment, and prevention.

Association between TUG and Anthropometric Values, Vibration Perception Threshold, FHSQ and 15-D in Type 2 Diabetes Mellitus Patients

Background: Diabetes Mellitus (DM) is a chronic disease and it is characterized by reduced insulin sensitivity and/or impaired insulin production. It affects approximately 415 million people worldwide and involves a variety of complications. DM has a number of complications, including diabetic neuropathy. All of these complications can have effects on body composition, vibration perception threshold (VPT), foot health and health-related quality of life (HRQoL). Objective: The aim of this study is to determine the correlation between the Timed Up and Go (TUG), VPT, Foot Health Status Questionnaire and 15-D Questionnaire in type 2 diabetes mellitus (T2DM) patients. Methodology: A total of 90 T2DM patients (56 men and 34 women) were evaluated on their body composition, VPT, the foot health status through the FHSQ, the HRQoL was evaluated through the 15-D Questionnaire and the TUG test was performed. Results: Statistically significant associations were found between TUG and lean and fat mass, VPT, the sections "General Foot Health" and "Physical Activity" in the FHSQ questionnaire, and the 15D total score and its sections "Mobility" and "Depression". Conclusions: There is a moderate direct correlation between the Timed Up and Go and the fat mass percentage and the vibration perception threshold. Moreover, there is a moderate inverse correlation between Timed Up and Go and fat-free mass, foot health and health-related quality of life in T2DM patients. Therefore, Timed Up and Go can be a tool to assist clinicians in monitoring and managing T2DM patients.

Chronic kidney disease and peripheral nerve function in the Health, Aging and Body Composition Study

BACKGROUND

Chronic kidney disease (CKD) is associated with poor mobility. Peripheral nerve function alterations play a significant role in low mobility. We tested the hypothesis that early CKD is associated with altered sensory, motor and autonomic nerve function.

METHODS

Participants in the Health, Aging and Body Composition cohort who had kidney function measures in Year 3 (1999-2000) and nerve function measurements at Year 4 (2000-01) were analyzed (n = 2290). Sensory (vibration threshold, monofilament insensitivity to light and standard touch), motor [compound motor action potentials (CMAPs), nerve conduction velocities (NCVs)] and autonomic (heart rate response and recovery after a 400-m walk test) nerve function as well as participant characteristics were compared across cystatin C- and creatinine-based estimated glomerular filtration rate categorized as ≤60 (CKD) or >60 mL/min/1.73 m2 (non-CKD). The association between CKD and nerve function was examined with logistic regression adjusted for covariates.

RESULTS

Participants with CKD (n = 476) were older (77 ± 3 versus 75 ± 3 years; P < 0.05) and had a higher prevalence of diabetes (20.6% versus 13.1%; P < 0.001). CKD was associated with higher odds for vibration detection threshold {odds ratio [OR] 1.7 [95% confidence interval (CI) 1.1-2.7]} and light touch insensitivity [OR 1.4 (95% CI 1.1-1.7)]. CMAPs and NCVs were not significantly different between CKD and non-CKD patients. In adjusted analyses, participants with CKD had higher odds of an abnormal heart rate response [OR 1.6 (95% CI 1.1-2.2)] and poor heart rate recovery [OR 1.5 (95% CI 1.1-2.0)].

CONCLUSIONS

CKD is associated with changes in sensory and autonomic nerve function, even after adjustment for demographics and comorbidities, including diabetes. Longitudinal studies in CKD are needed to determine the contribution of nerve impairments to clinically important outcomes.

Test-Retest Reliability of Kinematic Parameters of Timed Up and Go in People with Type 2 Diabetes

Diabetes mellitus is a chronic disease defined as a state of hyperglycaemia in fasting or postprandial states. Patients with type 2 diabetes mellitus (T2DM) often show reduced physical function, including low levels of strength, balance or mobility. In this regard, the timed up and go (TUG) is a widely used physical fitness test in people with T2DM. However, there is a lack of studies evaluating the properties TUG in this population. The present study aimed to evaluate the test-retest reliability of kinetic and kinematic parameters obtained from TUG in the diabetic population with different levels of diabetic neuropathy. A total of 56 patients with T2DM participated in the study. They were divided into three groups according to the vibration threshold: (a) severe neuropathy, (b) moderate neuropathy and (c) normal perception. The TUG was performed using two force platforms to assess kinematic measurements. The results show that both kinetic and kinematic variables had good to excellent reliability. The reliability of TUG was excellent for the whole sample and the groups with non-severe neuropathy. However, it was just good for the group with severe neuropathy.

Multiple Sensory Impairment Is Associated With Increased Risk of Dementia Among Black and White Older Adults

BACKGROUND

Few studies have examined impairment in multiple senses (multisensory impairment) and risk of dementia in comparison to having a single or no sensory impairment.

METHODS

We studied 1,810 black and white nondemented participants from Health, Aging, and Body Composition (Health ABC) Study aged 70-79 years at enrollment. Sensory impairment was determined at our study baseline (Year 3-5 of Health ABC) using established cut points for vision (Bailey-Lovie visual acuity and Pelli-Robson contrast sensitivity test), hearing (audiometric testing), smell (12-item Cross-Cultural Smell Identification Test), and touch (peripheral nerve function tests). Incident dementia over 10 years of follow-up was based on hospitalization records, dementia medications, or at least 1.5 SD decline in Modified Mini-Mental State Examination score (race-specific). Cox proportional hazard models with adjustment for demographics, health behaviors, and health conditions evaluated the relationship between risk of dementia and increasing number of sensory impairments.

RESULTS

Sensory impairments were common: 28% had visual impairment, 35% had hearing loss, 22% had poor smell, 12% had touch insensitivity; 26% had more than two impairments, and 5.6% had more than three sensory impairments. Number of impairments was associated with risk of dementia in a graded fashion (p < .001). Compared to no sensory impairments, the adjusted hazard ratio was 1.49 (95% CI: 1.12, 1.98) for one sensory impairment, 1.91 (95% CI: 1.39, 2.63) for two sensory impairments, and 2.85 (95% CI: 1.88, 4.30) for more than three sensory impairments.

CONCLUSIONS

Multisensory impairment was strongly associated with increased risk of dementia. Although, the nature of this relationship needs further investigation, sensory function assessment in multiple domains may help identify patients at high risk of dementia.

Neuromuscular Attributes Associated With Lower Extremity Mobility Among Community-Dwelling Older Adults

BACKGROUND

The Short Physical Performance Battery (SPPB) is advocated as a screening tool in geriatric care for predicting future disability. We aimed to identify the leg neuromuscular attributes to be targeted in rehabilitative care among older adults with poor SPPB scores.

METHODS

Boston Rehabilitative Impairment Study of the Elderly (Boston RISE) participants (n = 430) underwent assessment of neuromuscular attributes (leg strength, leg velocity, trunk extensor endurance, knee flexion range of motion [ROM], ankle ROM, and foot sensation). Linear regression models examined association between each neuromuscular attribute and SPPB, adjusting for age, race, gender, comorbidity, body mass index, depression, cognition, and other neuromuscular attributes.

RESULTS

Participants with 1 SD unit higher leg strength, leg velocity, and trunk extensor endurance had 0.52, 0.30, and 0.52 points higher SPPB total score. Participants with ankle ROM impairment and foot sensory loss had 0.43 and 0.57 lower SPPB total score compared with those without these. Leg strength and trunk extensor endurance were associated with balance; leg velocity, trunk extensor endurance, and ankle ROM were associated with gait speed; and strength, trunk extensor endurance, knee ROM, and feet sensation were associated with chair stand score. Neuromuscular attributes, along with covariates, explained 40.4% of the variance in the total SPPB score, a substantial increase over the 22.7% variance explained by covariates alone.

CONCLUSIONS

Neuromuscular attributes affect mobility performance in older patients as measured by the SPPB. Specific impairments are associated with poor performance in specific component scores. Assessment of the SPPB components and rehabilitation of associated impairments may help improve the functional performance among older adults.

Value-Added Electrodiagnostics: Targeting Interventions for Fall Risk Reduction

Walking confers numerous health benefits, particularly for middle-aged and older patients with diabetes and metabolic syndrome. Nevertheless, it brings a risk of injurious falls, especially among populations with diabetes and metabolic syndrome-related distal neuromuscular decline and frank neuropathy. Those who stand to benefit most from walking are at greatest risk. Development of practical clinical tools to more precisely quantify neuromuscular function and link it to mobility outcomes will help clinicians target interventions toward those at risk for falls. Electrodiagnosis, with inclusion of several newer techniques, serves as a promising tool for objective evaluation of distal neuromuscular function.

Low blood pressure levels for fall injuries in older adults: the Health, Aging and Body Composition Study

Fall injuries cause morbidity and mortality in older adults. We assessed if low blood pressure (BP) is associated with fall injuries, including sensitivity analyses stratified by antihypertensive medications, in community-dwelling adults from the Health, Aging and Body Composition Study (N = 1819; age 76.6 ± 2.9 years; 53% women; 37% black). Incident fall injuries (N = 570 in 3.8 ± 2.4 years) were the first Medicare claims event from clinic visit (7/00-6/01) to 12/31/08 with an ICD-9 fall code and non-fracture injury code, or fracture code with/without a fall code. Participants without fall injuries (N = 1249) were censored over 6.9 ± 2.1 years. Cox regression models for fall injuries with clinically relevant systolic BP (SBP; ≤ 120, ≤ 130, ≤ 140, > 150 mmHg) and diastolic BP (DBP; ≤ 60, ≤ 70, ≤ 80, > 90 mmHg) were adjusted for demographics, body mass index, lifestyle factors, comorbidity, and number and type of medications. Participants with versus without fall injuries had lower DBP (70.5 ± 11.2 vs. 71.8 ± 10.7 mmHg) and used more medications (3.8 ± 2.9 vs. 3.3 ± 2.7); all P < 0.01. In adjusted Cox regression, fall injury risk was increased for DBP ≤ 60 mmHg (HR = 1.25; 95% CI 1.02-1.53) and borderline for DBP ≤ 70 mmHg (HR = 1.16; 95% CI 0.98-1.37), but was attenuated by adjustment for number of medications (HR = 1.22; 95% CI 0.99-1.49 and HR = 1.12; 95% CI 0.95-1.32, respectively). Stratifying by antihypertensive medication, DBP ≤ 60 mmHg increased fall injury risk only among those without use (HR = 1.39; 95% CI 1.02-1.90). SBP was not associated with fall injury risk. Number of medications or underlying poor health may account for associations of low DBP and fall injuries.

Motor unit activity, force steadiness, and perceived fatigability are correlated with mobility in older adults

The purpose of our study was to examine the associations between the performance of older adults on four tests of mobility and the physical capabilities of the lower leg muscles. The assessments included measures of muscle strength, muscle activation, and perceived fatigability. Muscle activation was quantified as the force fluctuations-a measure of force steadiness-and motor unit discharge characteristics of lower leg muscles during submaximal isometric contractions. Perceived fatigability was measured as the rating of perceived exertion achieved during a test of walking endurance. Twenty participants (73 ± 4 yr) completed one to four evaluation sessions that were separated by at least 3 wk. The protocol included a 400-m walk, a 10-m walk at maximal and preferred speeds, a chair-rise test, and the strength, force steadiness, and discharge characteristics of motor units detected by high-density electromyography of lower leg muscles. Multiple-regression analyses yielded statistically significant models that explained modest amounts of the variance in the four mobility tests. The variance explained by the regression models was 39% for 400-m walk time, 33% for maximal walk time, 42% for preferred walk time, and 27% for chair-rise time. The findings indicate that differences in mobility among healthy older adults were partially associated with the level of perceived fatigability (willingness of individuals to exert themselves) achieved during the test of walking endurance and the discharge characteristics of soleus, medial gastrocnemius, and tibialis anterior motor units during steady submaximal contractions with the plantar flexor and dorsiflexor muscles. NEW & NOTEWORTHY Differences among healthy older adults in walking endurance, walking speed, and ability to rise from a chair can be partially explained by the performance capabilities of lower leg muscles. Assessments comprised the willingness to exert effort (perceived fatigability) and the discharge times of action potentials by motor units in calf muscles during submaximal isometric contractions. These findings indicate that the nervous system contributes significantly to differences in mobility among healthy older adults.

Impact of Osteoarthritis on Difficulty Walking: A Population-Based Study

OBJECTIVE

To assess the relationship of hip and knee osteoarthritis (OA) to walking difficulty.

METHODS

A population cohort ages ≤55 years recruited from 1996 to 1998 (n = 28,451) completed a standardized questionnaire assessing demographics, health conditions, joint symptoms, and functional limitations, including difficulty walking in the past 3 months. Survey data were linked to health administrative databases; self-report and administrative data were used to identify health conditions. Hip/knee OA was defined as self-reported swelling, pain, or stiffness in a hip or knee lasting ≥6 weeks in the past 3 months without an inflammatory arthritis diagnosis. Using multivariable logistic regression, we examined the determinants of walking difficulty and constructed a clinical nomogram.

RESULTS

A total of 18,490 cohort participants were eligible (mean age 68 years, 60% women), and 25% reported difficulty walking. Difficulty walking was significantly and independently associated with older age, female sex, body mass index, and several health conditions. Of the conditions examined, the likelihood of walking difficulty was greatest with hip and knee OA and increased with the number of hip/knee joints affected. The predicted probability of difficulty walking for a 60-year-old middle-income, normal-weight woman was 5-10% with no health conditions, 10-20% with diabetes mellitus and cardiovascular (CV) disease, 40% with OA in 2 hips/knees, 60-70% with diabetes mellitus, CV disease, and OA in 2 hips/knees, and 80% with diabetes mellitus, CV disease, and OA in all hips/knees.

CONCLUSION

In a population cohort, symptomatic hip/knee OA was the strongest contributor to walking difficulty. Given the importance of walking to engagement in physical activity for chronic disease management, greater attention to OA is warranted.

Relationship between sensorimotor peripheral nerve function and indicators of cardiovascular autonomic function in older adults from the Health, Aging and Body Composition Study

BACKGROUND

Age-related peripheral nervous system (PNS) impairments are highly prevalent in older adults. Although sensorimotor and cardiovascular autonomic function have been shown to be related in persons with diabetes, the nature of the relationship in general community-dwelling older adult populations is unknown.

METHODS

Health, Aging and Body Composition participants (n=2399, age=76.5±2.9years, 52% women, 38% black) underwent peripheral nerve testing at the 2000/01 clinic visit. Nerve conduction amplitude and velocity were measured at the peroneal motor nerve. Sensory nerve function was assessed with vibration detection threshold and monofilament (1.4-g/10-g) testing at the big toe. Symptoms of lower-extremity peripheral neuropathy were collected by self-report. Cardiovascular autonomic function indicators included postural hypotension, resting heart rate (HR), as well as HR response to and recovery from submaximal exercise testing (400m walk). Multivariable modeling adjusted for demographic/lifestyle factors, medication use and comorbid conditions.

RESULTS

In fully adjusted models, poor motor nerve conduction velocity (<40m/s) was associated with greater odds of postural hypotension, (OR=1.6, 95% CI: 1.0-2.5), while poor motor amplitude (<1mV) was associated with 2.3beats/min (p=0.003) higher resting HR. No associations were observed between sensory nerve function or symptoms of peripheral neuropathy and indicators of cardiovascular autonomic function.

CONCLUSIONS

Motor nerve function and indicators of cardiovascular autonomic function remained significantly related even after considering many potentially shared risk factors. Future studies should investigate common underlying processes for developing multiple PNS impairments in older adults.

Effect of Metabolic Syndrome on the Mobility Benefit of a Structured Physical Activity Intervention-The Lifestyle Interventions and Independence for Elders Randomized Clinical Trial

OBJECTIVES

To test whether structured physical activity (PA) is associated with a greater reduction in major mobility disability (MMD) in older persons with metabolic syndrome (MetS) than in those without.

DESIGN

Data from the Lifestyle Interventions and Independence for Elders (LIFE) Study, a multicenter randomized trial of 1,635 persons with assessments every 6 months (average 2.7 years).

SETTING

Eight U.S. centers.

PARTICIPANTS

Sedentary men and women aged 70 to 89 with functional limitations (N = 1,535); 100 participants were excluded because of missing MetS data.

INTERVENTION

Participants were randomized to a moderate-intensity PA program (n = 766) or a health education program (n = 769).

MEASUREMENTS

MetS was defined according to the 2009 multiagency harmonized criteria. Outcomes included incident MMD (loss of ability to walk 400 m) and persistent MMD (two consecutive MMD diagnoses or one MMD diagnosis followed by death).

RESULTS

Seven hundred sixty-three (49.7%) participants met criteria for MetS. PA reduced incident MMD more than health education did in participants with MetS (hazard ratio (HR) = 0.72, 95% confidence interval (CI) = 0.57-0.91, P = .007) but not in those without MetS (HR = 0.96, 95% CI = 0.73-1.25, P = .75); the test for statistical interaction was not significant (P = .13). PA reduced the risk of persistent MMD in participants with MetS (HR = 0.57, 95% CI = 0.41-0.79, P < .001) but not in those without MetS (HR = 0.97, 95% CI = 0.67-1.41, P = .87). The test for statistical interaction was significant (P = .04).

CONCLUSION

Moderate-intensity PA substantially reduces the risk of persistent MMD in older persons with functional limitations with MetS but not in those without MetS. Comparable results were observed for incident MMD. The LIFE PA program may be an effective strategy for reducing mobility disability in vulnerable older persons with MetS.

Cancer and treatment-related symptoms are associated with mobility disability in women with ovarian cancer: A cross-sectional study

OBJECTIVE

To examine the prevalence of symptom-related mobility disability and identify specific symptoms and other factors associated with mobility disability among a national sample of ovarian cancer (OC) survivors.

METHODS

Descriptive, correlational secondary analysis of a National Ovarian Cancer Coalition mailed survey of women with a history of OC (n=713). We used the Symptom Representation Questionnaire (SRQ), the MD Anderson Symptom Inventory (MDASI) Interference Scale, and medical and demographic information to determine prevalence of symptom-related mobility disability. We constructed a multiple linear regression model to determine the relative contributions of specific symptoms and other factors to mobility disability.

RESULTS

A majority of the sample (60.0%) reported symptom-related mobility disability. Independent predictors included: > one comorbidity (β=0.112, p=0.001), active OC (β=0.111, p=0.037), abdominal bloating (β=0.097, p=0.006), fatigue (β=0.314, p<0.001), lack of appetite (β=0.072, p=0.045), numbness/tingling (β=0.134, p<0.001), and pain (β=0.194, p<0.001). The model explained 41.5% of the variance in symptom-related mobility disability (R²=0.415). Unexpectedly, age (β=-0.028, p=0.412) and current chemotherapy (β=0.107, p=0.118) were not significant predictors.

CONCLUSIONS

Symptom-related mobility disability is common among women with OC and is associated with medical comorbidities, abdominal bloating, fatigue, lack of appetite, numbness/tingling, and pain. Longitudinal research should clarify the relationship of these symptoms to mobility disability and determine whether effective symptom management minimizes disability.

Age-Related Change in Mobility: Perspectives From Life Course Epidemiology and Geroscience

Mobility is the most studied and most relevant physical ability affecting quality of life with strong prognostic value for disability and survival. Natural selection has built the "engine" of mobility with great robustness, redundancy, and functional reserve. Efficient patterns of mobility can be acquired during development even by children affected by severe impairments. Analogously, age-associated impairments in mobility-related physiological systems are compensated and overt limitations of mobility only occur when the severity can no longer be compensated. Mobility loss in older persons usually results from multiple impairments in the central nervous system, muscles, joints, and energetic and sensory physiological systems. Early preclinical changes in these physiological systems that precede mobility loss have been poorly studied. Peak performance, rate of decline, compensatory behaviors, or subclinical deterioration of physiological resources may cumulatively influence both timing of mobility loss and chances of recovery, but their role as risk factors has not been adequately characterized. Understanding the natural history of these early changes and intervening on them would likely be the most effective strategy to reduce the burden of disability in the population. For example, young women with low bone peak mass could be counseled to start strength resistance exercise to reduce their high risk of developing osteoporosis and fracture later in life. Expanding this approach to other physiological domains requires collecting and interpreting data from life course epidemiological studies, establishing normative measures of mobility, physical function, and physical activity, and connecting them with life course trajectories of the mobility-relevant physiological domains.

Sensorimotor Peripheral Nerve Function and Physical Activity in Older Men

We determined whether sensorimotor peripheral nerve (PN) function was associated with physical activity (PA) in older men. The Osteoporotic Fractures in Men Study Pittsburgh, PA, site (n = 328, age 78.8 ± 4.7 years) conducted PN testing, including: peroneal motor and sural sensory nerve conduction (latencies, amplitudes: CMAP and SNAP for motor and sensory amplitude, respectively), 1.4g/10g monofilament (dorsum of the great toe), and neuropathy symptoms. ANOVA and multivariate linear regression modeled PN associations with PA (Physical Activity Scale for the Elderly [PASE] and SenseWear Armband). After multivariable adjustment, better motor latency was associated with higher PASE scores (160.5 ± 4.8 vs. 135.6 ± 6.7, p < .01). Those without versus with neuropathy symptoms had higher PASE scores (157.6 ± 5.3 vs. 132.9 ± 7.1, p < .01). Better versus worse SNAP was associated with slightly more daily vigorous activity (9.5 ± 0.8 vs. 7.3 ± 0.7, p = .05). Other PN measures were not associated with PA. Certain PN measures were associated with lower PA, suggesting a potential pathway for disability.

Sensory-motor training targeting motor dysfunction and muscle weakness in long-term care elderly combined with motivational strategies: a single blind randomized controlled study

BACKGROUND

This study evaluated the effects of a combined innovative training regime consisting of stochastic resonance whole-body vibration (SR-WBV) and a dance video game (DVG) on physical performance and muscle strength in long-term-care dwelling elderly.

METHODS

Thirthy long-term-care elderly were randomly allocated to an intervention group (IG; n = 16) receiving combined SR-WBV training and DVG, or a sham group (SG; n = 14). IG performed five sets one minute of SR-WBV, with one minute rest between sets (base frequency 3 Hz up to 6 Hz, Noise 4) during the first five weeks on three days per week. From week five to eight a DVG was added to SR-WBV for IG on three days per week. SG performed a five-set SR-WBV program (1 Hz, Noise 1) lasting five times one minute, with one minute rest in between, three days a week. From week five to eight stepping exercises on a trampoline were added on three days per week.

PRIMARY OUTCOME

Short physical performance battery (SPPB). Secondary outcome: isometric maximal voluntary contraction (IMVC), and sub phases of IMVC (Fsub), isometric rate of force development (IRFD) and sub time phases of IRFD (IRFDsub) were measured at baseline, after four and eight weeks. ANOVA with repeated measures was used for analyses of time and interaction effects and MANOVA determined between group intervention effects.

RESULTS

Between group effects revealed significant effects on the SPPB primary outcome after four weeks F(1, 27) = 6.17; p = 0.02) and after eight weeks F(1,27) = 11.8; p = 0.002). Secondary muscle function related outcome showed significant between group effects in IG on IRFD, Fsub 30 ms, 100 ms, 200 ms and IRFDsub 0-30 ms, 0-50 ms, 0-100 ms and 100-200 ms compared to SG (all p < 0.05).

CONCLUSIONS

Eight weeks SR-WBV and DVG intervention improved lower extremity physical function and muscle strength compared to a sham intervention in long-term-care elderly. SR-WBV and DVG seems to be effective as a training regime for skilling up in long-term-care elderly.

Metabolic Syndrome Components Are Associated With Symptomatic Polyneuropathy Independent of Glycemic Status

OBJECTIVE

Previous studies demonstrate that the metabolic syndrome is associated with distal symmetric polyneuropathy (DSP). We aimed to determine the magnitude of this effect and the precise components involved.

RESEARCH DESIGN AND METHODS

We determined the symptomatic DSP prevalence in the Health, Aging, and Body Composition (Health ABC) study (prospective cohort study, with subjects aged 70-79 years at baseline), stratified by glycemic status (glucose tolerance test) and the number of additional metabolic syndrome components (updated National Cholesterol Education Program/Adult Treatment Panel III definition). DSP was defined as neuropathic symptoms (questionnaire) plus at least one of three confirmatory tests (heavy monofilament, peroneal conduction velocity, and vibration threshold). Multivariable logistic and linear regression evaluated the association of metabolic syndrome components with DSP in cross-sectional and longitudinal analyses.

RESULTS

Of 2,382 participants with neuropathy measures (mean age 73.5 ± 2.9 years, 38.2% black, 51.7% women), 21.0% had diabetes, 29.9% prediabetes, 52.8% metabolic syndrome, and 11.1% DSP. Stratified by glycemic status, DSP prevalence increased as the number of metabolic syndrome components increased (P = 0.03). Diabetes (cross-sectional model, odds ratio [OR] 1.65 [95% CI 1.18-2.31]) and baseline hemoglobin A1C (longitudinal model, OR 1.42 [95% CI 1.15-1.75]) were the only metabolic syndrome measures significantly associated with DSP. Waist circumference and HDL were significantly associated with multiple secondary neuropathy outcomes.

CONCLUSIONS

Independent of glycemic status, symptomatic DSP is more common in those with additional metabolic syndrome components. However, the issue of which metabolic syndrome components drive this association, in addition to hyperglycemia, remains unclear. Larger waist circumference and low HDL may be associated with DSP, but larger studies with more precise metabolic measures are needed.

Sensorimotor Peripheral Nerve Function and the Longitudinal Relationship With Endurance Walking in the Health, Aging and Body Composition Study

OBJECTIVES

To determine whether lower extremity sensorimotor peripheral nerve deficits are associated with reduced walking endurance in older adults.

DESIGN

Prospective cohort study with 6 years of follow-up.

SETTING

Two university research clinics.

PARTICIPANTS

Community-dwelling older adults enrolled in the Health, Aging and Body Composition Study from the 2000-2001 annual clinical examination (N=2393; mean age ± SD, 76.5±2.9y; 48.2% men; 38.2% black) and a subset with longitudinal data (n=1178).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Participants underwent peripheral nerve function examination in 2000-2001, including peroneal motor nerve conduction amplitude and velocity, vibration perception threshold, and monofilament testing. Symptoms of lower extremity peripheral neuropathy included numbness or tingling and sudden stabbing, burning, pain, or aches in the feet or legs. The Long Distance Corridor Walk (LDCW) (400 m) was administered in 2000-2001 and every 2 years afterward for 6 years to assess endurance walking performance over time.

RESULTS

In separate, fully adjusted linear mixed models, poor vibration threshold (>130 μm), 10-g and 1.4-g monofilament insensitivity were each associated with a slower 400-m walk completion time (16.0 s, 14.4s, and 6.9 s slower, respectively; P<.05 for each). Poor motor amplitude (<1 mV), poor vibration perception threshold, and 10-g monofilament insensitivity were related to greater slowing per year (4.7, 4.2, and 3.8 additional seconds per year, respectively; P<.05), although poor motor amplitude was not associated with initial completion time.

CONCLUSIONS

Poorer sensorimotor peripheral nerve function is related to slower endurance walking and greater slowing longitudinally. Interventions to reduce the burden of sensorimotor peripheral nerve function impairments should be considered to help older adults maintain walking endurance-a critical component for remaining independent in the community.

Mobility-Related Consequences of Reduced Lower-Extremity Peripheral Nerve Function with Age: A Systematic Review

The objective of this study is to systematically review the relationship between lower-extremity peripheral nerve function and mobility in older adults. The National Library of Medicine (PubMed) was searched on March 23, 2015 with no limits on publication dates. One reviewer selected original research studies of older adults (≥65 years) that assessed the relationship between lower-extremity peripheral nerve function and mobility-related outcomes. Participants, study design and methods of assessing peripheral nerve impairment were evaluated and results were reported and synthesized. Eight articles were identified, including 6 cross-sectional and 2 longitudinal studies. These articles investigated 6 elderly cohorts (4 from the U.S. and 2 from Italy): 3 community-dwelling (including 1 with only disabled women and 1 without mobility limitations at baseline), 1 with both community-dwelling and institutionalized residents, 1 from a range of residential locations, and 1 of patients with peripheral arterial disease. Mean ages ranged from 71-82 years. Nerve function was assessed by vibration threshold (n=2); sensory measures and clinical signs and symptoms of neuropathy (n=2); motor nerve conduction (n=1); and a combination of both sensory measures and motor nerve conduction (n=3). Each study found that worse peripheral nerve function was related to poor mobility, although relationships varied based on the nerve function measure and mobility domain assessed. Six studies found that the association between nerve function and mobility persisted despite adjustment for diabetes. Evidence suggests that peripheral nerve function impairment at various levels of severity is related to poor mobility independent of diabetes. Relationships varied depending on peripheral nerve measure, which may be particularly important when investigating specific biological mechanisms. Future research needs to identify risk factors for peripheral nerve decline beyond diabetes, especially those common in late-life and modifiable. Interventions to preserve nerve function should be investigated with regard to their effect on postponing or preventing disability in older adults.

Sensory Functions, Balance, and Mobility in Older Adults With Type 2 Diabetes Without Overt Diabetic Peripheral Neuropathy: A Brief Report

This study examined possible subtle degradation in sensory functions, balance, and mobility in older adults with type 2 diabetes (T2D) prior to overt development of diabetic peripheral neuropathy (DPN). Twenty-five healthy controls (HC group, age = 74.6 ± 5.4) and 35 T2D elderly without DPN (T2D group, age = 70.6 ± 4.7) were recruited. Sensory assessment included vibrotactile sensitivity, bilateral caloric weakness, and visual contrast sensitivity. Self-report measures comprised of Activity-Specific Balance Confidence (ABC), Human Activity Profile–adjusted activity scores (HAP-AAS), falls, and mobility disability. Performance measures included modified Timed-Up and Go (mTUG), Clinical Test of Sensory Integration for Balance (mCTSIB), and Frailty and Injuries (FICSIT-4) balance test. T2D group demonstrated significantly worse bilateral caloric weakness, marginally higher threshold of vibrotactile sensitivity and lower visual contrast sensitivity, and as well as signifcantly lower HAP-AAS. A significantly higher proportion of the T2D group failed mCTSIB Condition 4 than in the HC group. Subtle changes in multiple sensory systems of older adults with T2D may reduce redundancy available for balance control while performing challenging activities much before DPN development.