Cognitive and Motor Cortical Activity During Cognitively Demanding Stepping Tasks in Older People at Low and High Risk of Falling

Cognitive functioning and falls in older people: A systematic review and meta-analysis

OBJECTIVE

To identify which cognitive functions and specific neuropsychological assessments predict falls in older people living in the community.

METHODS

Five electronic databases were searched until 30/08/2022 for studies assessing the association between specific cognitive functions and faller status (prospective and retrospective), in community-dwelling older people. Risk of bias was assessed with the Newcastle-Ottawa Scale. Meta-analyses synthesised the evidence regarding the associations between different neurocognitive subdomains and faller status.

RESULTS

Thirty-eight studies (20 retrospective, 18 prospective) involving 37,101 participants were included. All but one study was rated high or medium quality. Meta-analyses were performed with data from 28 studies across 11 neurocognitive subdomains and four specific neuropsychological tests. Poor cognitive flexibility, processing speed, free recall, working memory and sustained attention were significantly associated with faller status, but poor verbal fluency, visual perception, recognition memory, visuo-constructional reasoning and language were not. The Trail Making Test B was found to have the strongest association with faller status.

CONCLUSION

Poor performance in neurocognitive subdomains spanning processing speed, attention, executive function and aspects of memory are associated with falls in older people, albeit with small effect sizes. The Trail Making Test, a free-to-use, simple assessment of processing speed and mental flexibility, is recommended as the cognitive screening test for fall risk in older people.

Reliability and Validity of Four Step Tests in Older Adults With Dementia

OBJECTIVES

To determine the test-retest and inter-rater reliability, concurrent and discriminative validity of the Four Square Step Test (FSST), the Choice Stepping Reaction Time Test (CSRTT), the Maximum Step Length Test (MSLT), and the Alternate Step Test (AST) in older adults with dementia.

METHODS

Thirty-seven older adults with dementia who could walk independently for at least 10 m were recruited at community centers and day care centers for older adults. The participants completed the step tests conducted by two independent raters on three separate testing occasions within 3 weeks. In addition, the physical and cognitive function of the participants were evaluated at baseline.

RESULTS

The FSST, CSRTT, and MSLT showed good-to-excellent test-retest reliability (intraclass correlation coefficient [ICC] = 0.83-0.91), and the AST exhibited fair test-retest reliability (ICC = 0.70). All the step tests showed good-to-excellent inter-rater reliability (ICC = 0.75-0.94). The step tests had moderate-to-strong correlations with various physical and cognitive measures (Pearson correlation coefficients = 0.34-0.72). The MSLT side step and AST could differentiate between individuals who did and did not use a walking stick to ambulate (p ≤ 0.046). The FSST, CSRTT, and AST could differentiate between individuals with and without a major neurocognitive impairment (p ≤ 0.005).

CONCLUSION

The FSST, CSRTT, and MSLT were reliable and valid for examining the stepping performance of older adults with dementia. Clinicians can use these tests to evaluate the physical and cognitive function of this population and identify those with significant cognitive impairment.

TRIAL REGISTRATION

Clinical Trial Registration number: NCT04296123.

Early screening of post-stroke fall risk: A simultaneous multimodal fNIRs-EMG study

BACKGROUND

Stroke is the third-leading cause of death and disability, and poststroke falls (PSF) are common at all stages after stroke and could even lead to injuries or death. Brain information from functional near-infrared spectroscopy (fNIRs) may precede conventional imaging and clinical symptoms but has not been systematically considered in PSF risk prediction. This study investigated the difference in brain activation between stroke patients and healthy subjects, and this study was aimed to explore fNIRs biomarkers for early screening of PSF risk by comparing the brain activation in patients at and not at PSF risk.

METHODS

In this study, we explored the differences in brain activation and connectivity between stroke and healthy subjects by synchronizing the detection of fNIRs and EMG tests during simple (usual sit-to-stand) and difficult tasks (sit-to-stand based on EMG feedback). Thereby further screened for neuroimaging biomarkers for early prediction of PSF risk by comparing brain activation variability in poststroke patients at and not at fall risk during simple and difficult tasks. The area under the ROC curve (AUROC), sensitivity, and specificity were used to compare the diagnostic effect.

RESULTS

A total of 40 patients (22 not at and 18 at PSF risk) and 38 healthy subjects were enrolled. As the difficulty of standing task increased, stroke patients compared with healthy subjects further increased the activation of the unaffected side of supplementary motor area (H-SMA) and dorsolateral prefrontal cortex-Brodmann area 46 (H-DLFC-BA46) but were unable to increase functional connectivity (Group*Task: p < 0.05). More importantly, the novel finding showed that hyperactivation of the H-SMA during a simple standing task was a valid fNIRs predictor of PSF risk [AUROC 0.74, p = 0.010, sensitivity 77.8%, specificity 63.6%].

CONCLUSIONS

This study provided novel evidence that fNIR-derived biomarkers could early predict PSF risk that can facilitate the widespread use of real-time assessment tools in early screening and rehabilitation. Meanwhile, this study demonstrated that the higher brain activation and inability to increase the brain functional connectivity in stroke patients during difficult task indicated the inefficient use of brain resources.

The effect of transcranial direct current stimulation associated with video game training on the postural balance of older women in the community: A blind, randomized, clinical trial

BACKGROUND

Falls are frequent in older adults and can cause trauma, injury, and death. Fall prevention with virtual reality presents good results in improving postural control. Transcranial Direct Current Stimulation (tDCS) has been used with the same aim; however, the combination of the two techniques has still been little studied.

PURPOSE

To assess whether tDCS can enhance the effect of video game training (VGT) on improving the postural balance of healthy older women.

METHOD

A blinded, randomized, controlled clinical trial was conducted with 57 older women who were randomized to three balance training groups: Control Group (VGT), Anodal Group (VGT combined with anodic tDCS-atDCS), and Sham Group (VGT combined with sham tDCS-stDCS). Balance training was performed twice a week for four weeks, totalizing eight 20-min sessions using VGT associated with tDCS. Postural balance was assessed pre-and post-training and 30 days after the end of the eight sessions using the Mini-Balance Evaluation Systems Test.

RESULTS

Compared to pre-intervention the Mini BEST test increased similarly in the three groups in post-intervention (control: pre 23.7 ± 2.8 to post 27.0 ± 2.2; anodal: pre 24.4 ± 1 to post 27.7 ± 0.8 and sham: pre 24.2 ± 1.9 to post 26.5 ± 1.6; p < 0.001) and follow-up (control: pre 23.7 ± 2.8 to follow-up 26.8 ± 2.3; anodal: pre 24.4 ± 1 to follow-up 27.3 ± 1.4 and sham: pre 24.2 ± 1.9 to follow-up 26.8 ± 1.5; p < 0.001).

CONCLUSION

There was an improvement in the postural balance of the three training groups that were independent of tDCS.

DISCUSSION

Some studies have shown the positive tDCS effects associated with other tasks to improve balance. However, these results convey the effects of only anodic-tDCS compared to sham-tDCS. Possibly, the effect of VGT surpassed the tDCS effects, promoting a ceiling effect from the combination of these two therapies. However, studies with other therapies combined with tDCS for older adults deserve to be investigated, as well as in frail older people.

Left and Right Cortical Activity Arising from Preferred Walking Speed in Older Adults

Cortical activity and walking speed are known to decline with age and can lead to an increased risk of falls in the elderly. Despite age being a known contributor to this decline, individuals age at different rates. This study aimed to analyse left and right cortical activity changes in elderly adults regarding their walking speed. Cortical activation and gait data were obtained from 50 healthy older individuals. Participants were then grouped into a cluster based on their preferred walking speed (slow or fast). Analyses on the differences of cortical activation and gait parameters between groups were carried out. Within-subject analyses on left and right-hemispheric activation were also performed. Results showed that individuals with a slower preferred walking speed required a higher increase in cortical activity. Individuals in the fast cluster presented greater changes in cortical activation in the right hemisphere. This work demonstrates that categorizing older adults by age is not necessarily the most relevant method, and that cortical activity can be a good indicator of performance with respect to walking speed (linked to fall risk and frailty in the elderly). Future work may wish to explore how physical activity training influences cortical activation over time in the elderly.

Changes in cortical activation during upright stance in individuals with chronic low back pain: An fNIRS study

Introduction

Postural control deficits are a potential cause of persistent and recurrent pain in patients with chronic low back pain (CLBP). Although some studies have confirmed that the dorsolateral prefrontal cortex (DLPFC) contributes to pain regulation in CLBP, its role in the postural control of patients with CLBP remains unclear. Therefore, this study aimed to investigate the DLPFC activation of patients with CLBP and healthy controls under different upright stance task conditions.

Methods

Twenty patients with CLBP (26.50 ± 2.48 years) and 20 healthy controls (25.75 ± 3.57 years) performed upright stance tasks under three conditions: Task-1 was static balance with eyes open; Task-2 was static balance with eyes closed; Task-3 involved dynamic balance on an unstable surface with eyes open. A wireless functional near-infrared spectroscopy (fNIRS) system measured cortical activity, including the bilateral DLPFC, pre-motor cortex (PMC) and supplementary motor area (SMA), the primary motor cortex (M1), the primary somatosensory cortex (S1), and a force platform measured balance parameters during upright stance.

Results

The two-way repeated measures ANOVA results showed significant interaction in bilateral PMC/SMA activation. Moreover, patients with CLBP had significantly increased right DLPFC activation and higher sway 32 area and velocity than healthy controls during upright stance.

Discussion

Our results imply that PMC/SMA and DLPFC maintain standing balance. The patients with CLBP have higher cortical activity and upright stance control deficits, which may indicate that the patients with CLBP have low neural efficiency and need more motor resources to maintain balance.

The risk of falls among the aging population: A systematic review and meta-analysis

Aim

This study aims to clarify the risk factors for falls to prevent severe consequences in older adults.

Methods

We searched the PubMed, Web of Science, Embase, and Google Scholar databases using the terms "risk factors" OR "predicting factors" OR "predictor" AND "fall" OR "drop" to identify all relevant studies and compare their results. The study participants were divided into two groups, the "fall group" and the "control group", and differences in demographic characteristics, lifestyles, and comorbidities were compared.

Results

We included 34 articles in the analysis and analyzed 22 factors. Older age, lower education level, polypharmacy, malnutrition, living alone, living in an urban area, smoking, and alcohol consumption increased the risk of falls in the aging population. Additionally, comorbidities such as cardiac disease, hypertension, diabetes, stroke, frailty, previous history of falls, depression, Parkinson's disease, and pain increased the risk of falls.

Conclusion

Demographic characteristics, comorbidities, and lifestyle factors can influence the risk of falls and should be taken into consideration.