Qualitative neurological gait abnormalities, cardiovascular risk factors and functional status in older community-dwellers without neurological diseases: The Healthy Brain Project

Linking Dementia Pathology and Alteration in Brain Activation to Complex Daily Functional Decline During the Preclinical Dementia Stages: Protocol for a Prospective Observational Cohort Study

BACKGROUND

Progressive difficulty in performing everyday functional activities is a key diagnostic feature of dementia syndromes. However, not much is known about the neural signature of functional decline, particularly during the very early stages of dementia. Early intervention before overt impairment is observed offers the best hope of reducing the burdens of Alzheimer disease (AD) and other dementias. However, to justify early intervention, those at risk need to be detected earlier and more accurately. The decline in complex daily function (CdF) such as managing medications has been reported to precede impairment in basic activities of daily living (eg, eating and dressing).

OBJECTIVE

Our goal is to establish the neural signature of decline in CdF during the preclinical dementia period.

METHODS

Gait is central to many CdF and community-based activities. Hence, to elucidate the neural signature of CdF, we validated a novel electroencephalographic approach to measuring gait-related brain activation while participants perform complex gait-based functional tasks. We hypothesize that dementia-related pathology during the preclinical period activates a unique gait-related electroencephalographic (grEEG) pattern that predicts a subsequent decline in CdF.

RESULTS

We provide preliminary findings showing that older adults reporting CdF limitations can be characterized by a unique gait-related neural signature: weaker sensorimotor and stronger motor control activation. This subsample also had smaller brain volume and white matter hyperintensities in regions affected early by dementia and engaged in less physical exercise. We propose a prospective observational cohort study in cognitively unimpaired older adults with and without subclinical AD (plasma amyloid-β) and vascular (white matter hyperintensities) pathologies. We aim to (1) establish the unique grEEG activation as the neural signature and predictor of decline in CdF during the preclinical dementia period; (2) determine associations between dementia-related pathologies and incidence of the neural signature of CdF; and (3) establish associations between a dementia risk factor, physical inactivity, and the neural signature of CdF.

CONCLUSIONS

By establishing the clinical relevance and biological basis of the neural signature of CdF decline, we aim to improve prediction during the preclinical stages of ADs and other dementias. Our approach has important research and translational implications because grEEG protocols are relatively inexpensive and portable, and predicting CdF decline may have real-world benefits.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/56726.

Neural signature of mobility-related everyday function in older adults at-risk of cognitive impairment

Assessment of everyday activities is central to the diagnosis of dementia. Yet, little is known about brain processes associated with everyday functional limitations, particularly during early stages of cognitive decline. Twenty-six older adults (mean = 74.9 y) were stratified by risk using the Montreal Cognitive Assessment battery (MoCA, range: 0- 30) to classify individuals as higher (22-26) and lower risk (27+) of cognitive impairment. We investigated everyday function using a gait task designed to destabilize posture and applied Mobile Brain/Body Imaging. We predicted that participants would increase step width to gain stability, yet the underlying neural signatures would be different for lower versus higher risk individuals. Step width and fronto-parietal activation increased during visually perturbed input. Frontomedial theta increased in higher risk individuals during perturbed and unperturbed inputs. Left sensorimotor beta decreased in lower risk individuals during visually perturbed input. Modulations in theta and beta power were associated with MoCA scores. Our findings suggest that older adults at-risk of cognitive impairment can be characterized by a unique neural signature of everyday function.

The association between low cognitive reserve and subjective memory complaints in functionally independent older women

BACKGROUND

Several factors have been found to defend against pathologic cognitive decline in aging (i.e., cognitive reserve [CR]); however, other factors, including subjective memory complaints (SMC) and decreased functionality are considered early indicators of underlying neurocognitive dysfunction. Despite these known associations, the relationship between the presence of CR and SMC remains equivocal. This study sought to determine the relationship between objectively measured CR and SMC in a sample of functionally independent older women.

METHODS

This cross-sectional study recruited women aged ≥60 years who attended fitness or continuing education programs at the University for Seniors in Mexico City. Participants underwent a battery of physical and cognitive evaluations, including the Cognitive Reserve Questionnaire (CRQ), and were asked probing questions used to identify the presence of SMC.

RESULTS

The 269 participants had a median age of 69 years; most were single (40.5 %), lived alone (32.7 %), retired (58.2 %), well-educated (≥12 years of education), and functionally independent (89.2 %). 62 % scored "high" on the CRQ, while 9.3 % scored "low". After adjusting for multiple covariates, an independent association between CRQ score and the probability to have SMC was found (adjusted OR = 0.87, 95% CI 0.80-0.95, p-value = 0.002).

CONCLUSIONS

This study identified a relationship between low CR and the presence of SMC, independently of the cognitive function and motoric marker of muscle strength (i.e., low gait speed and handgrip strength) in functionally independent older women over 60y. This relationship remains independent of other variables such as age, symptoms of depression and instrumented activities of daily living.

Reliability of Lower Extremity Muscle Power and Functional Performance in Healthy, Older Women

Evaluation of the long-term reliability of muscle power and functional performance tests in older, healthy adults is warranted since determining whether performance is consistent over longer durations is more relevant for intervention studies. Objective. To assess the long-term test-retest reliability of measures of muscle power and lower body functional performance in healthy, nonexercising, older women. Methods. Data were derived from a nonexercising control group (n = 18; age = 73.3 (3.4) years; height = 159.6 (7.7) cm; body mass = 69.5 (12.7) kg; BMI = 27.3 (4.8)) of a randomized controlled trial of muscle power training in older women. Participants underwent lower extremity muscle power (Biodex) and functional testing (Short Physical Performance Battery, gait speed, 30-second chair stands, stair climbing, and 400-meter walk) at week 0 (baseline), 9, and 15. Results. For the upper leg, intraclass correlation coefficients (ICCs) were very high for knee extension power (0.90-0.97) and high to very high for knee flexion power (0.83-0.96). For lower-leg power, ICCs were high to very high for plantar flexion and dorsiflexion (0.83-0.96). ICCs for functional performance were moderate to very high (0.64-0.93). Coefficient of variation of the typical error (CV_TE) was <10.5% for knee extension/flexion power, 9.9-20.0% for plantar flexion/dorsiflexion power, and 1.9-14.9% for functional performance. Knee extension power and stair climb power demonstrated the highest reliability for muscle power and function, respectively. Mean values did not change over time, with the exception of the chair stands (p < 0.05); however, these changes were not considered clinically meaningful. Conclusions. The current study provides evidence supporting the long-term reliability of performance assessments of muscle power and lower body functional capacity over a period of up to 15 weeks in healthy, older women.

Double-task exercise programmes to strengthen cognitive and vascular health in older adults at risk of cognitive decline: protocol for a randomised clinical trial

INTRODUCTION

Cognitive and physical declines are frequent causes of disability among older adults (OAs) in Mexico that imposes significant burden on the health system and OAs' families. Programmes to prevent or delay OAs' cognitive and physical decline are scarce.

METHODS AND ANALYSIS

A double-blind randomised clinical trial will be conducted. The study will aim to evaluate two 24-week double-task (aerobic and cognitive) square-stepping exercise programmes for OAs at risk of cognitive decline-one programme with and another without caregiver participation-and to compare these with an aerobic-balance-stretching exercise programme (control group). 300 OAs (100 per group) affiliated with the Mexican Institute of Social Security (IMSS) between 60 and 65 years of age with self-reported cognitive concerns will participate. They will be stratified by education level and randomly allocated to the groups. The intervention will last 24 weeks, and the effect of each programme will be evaluated 12, 24 and 52 weeks after the intervention. Participants' demographic and clinical characteristics will be collected at baseline. The outcomes will include: (1) general cognitive function; (2) specific cognitive functions; (3) dual-task gait; (4) blood pressure; (5) carotid intima-media thickness; (6) OAs' health-related quality of life; and (7) caregiver burden. The effects of the interventions on each outcome variable will be examined using a repeated-measures analysis of variance (ANOVA), with study groups as the between-subjects variable and time as the within-subject variable.

ETHICS AND DISSEMINATION

The study was approved by the IMSS Ethics and Research Committees (registration number: 2018-785-095). All participants will sign a consent form prior to their participation. The study results will be disseminated to the IMSS authorities, healthcare providers and the research community.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT04068376).

Gait and balance disturbances are common in young urbanites and associated with cognitive impairment. Air pollution and the historical development of Alzheimer's disease in the young

To determine whether gait and balance dysfunction are present in young urbanites exposed to fine particular matter PM2.5 ≥ annual USEPA standard, we tested gait and balance with Tinetti and Berg tests in 575 clinically healthy subjects, age 21.0 ± 5.7 y who were residents in Metropolitan Mexico City, Villahermosa and Reynosa. The Montreal Cognitive Assessment was also applied to an independent cohort n:76, age 23.3 ± 9.1 y. In the 575 cohort, 75.4% and 34.4% had abnormal total Tinetti and Berg scores and high risk of falls in 17.2% and 5.7% respectively. BMI impacted negatively Tinetti and Berg performance. Gait dysfunction worsen with age and males performed worse than females. Gait and balance dysfunction were associated with mild cognitive impairment MCI (19.73%) and dementia (55.26%) in 57/76 and 19 cognitively intact subjects had gait and balance dysfunction. Seventy-five percent of urbanites exposed to PM2.5 had gait and balance dysfunction. For MMC residents-with historical documented Alzheimer disease (AD) and CSF abnormalities, these findings suggest Alzheimer Continuum is in progress. Early development of a Motoric Cognitive Risk Syndrome ought to be considered in city dwellers with normal cognition and gait dysfunction. The AD research frame in PM2.5 exposed young urbanites should include gait and balance measurements. Multicity teens and young adult cohorts are warranted for quantitative gait and balance measurements and neuropsychological and brain imaging studies in high vs low PM2.5 exposures. Early identification of gait and balance impairment in young air pollution-exposed urbanites would facilitate multidisciplinary prevention efforts for modifying the course of AD.