Vestibular Function in Older Adults With Cognitive Impairment: A Systematic Review

Just Keep Spinning? The Impact of Auditory and Somatosensory Cues on Rotary Chair Testing

PURPOSE

The purpose of this study was to determine whether providing realistic auditory or somatosensory cues to spatial location would affect measures of vestibulo-ocular reflex gain in a rotary chair testing (RCT) context.

METHOD

This was a fully within-subject design. Thirty young adults age 18-30 years (16 men, 14 women by self-identification) completed sinusoidal harmonic acceleration testing in a rotary chair under five different conditions, each at three rotational frequencies (0.01, 0.08, and 0.32 Hz). We recorded gain as the ratio of the amplitude of eye movement to chair movement using standard clinical procedures. The five conditions consisted of two without spatial information (silence, tasking via headphones) and three with either auditory (refrigerator sound, tasking via speaker) or somatosensory (fan) information. Two of the conditions also included mental tasking (tasking via headphones, tasking via speaker) and differed only in terms of the spatial localizability of the verbal instructions. We used linear mixed-effects modeling to compare pairs of conditions, specifically examining the effects of the availability of spatial cues in the environment. This study was preregistered on Open Science Framework (https://osf.io/2gqcf/).

RESULTS

Results showed significant effects of frequency in all conditions (p < .05), but the only pairs of conditions that were significantly different were those including tasking in one condition but not the other (e.g., tasking via headphones vs. silence). Post hoc equivalence testing showed that the lack of significance in the other comparisons could be confirmed as not meaningfully different.

CONCLUSIONS

These findings suggest that the presence of externally localizable sensory information, whether auditory or somatosensory, does not affect measures of gain in RCT to any relevant degree. However, these findings also contribute to the increasing body of evidence suggesting that mental engagement ("tasking") does increase gain whether or not it is provided via localizable instructions.

Association of Alzheimer's Disease With Peripheral Vestibular Disorder: A Case-Control Study

OBJECTIVES

Vestibular disorders can impact cognitive domains, including spatial orientation and memory, which are also affected in Alzheimer's disease. This study aimed to examine the association between Alzheimer's disease and a prior diagnosis of peripheral vestibular disorders in the elderly Taiwanese population.

METHODS

The case-control study sample was retrieved from Taiwan's Longitudinal Health Insurance Database 2010. We included 3138 cases with Alzheimer's disease and 9414 propensity-matched controls. We conducted multivariable logistic regression modeling to investigate the association between Alzheimer's disease and a prior diagnosis of peripheral vestibular disorders after accounting for sociodemographic characteristics and medical comorbidities including diabetes, coronary heart disease, hypertension, hyperlipidemia, and hearing loss.

RESULTS

The results revealed a statistically significant difference in the prevalence of prior peripheral vestibular disorders between patients with Alzheimer's disease and controls; 20.6% among patients with Alzheimer's disease and 11.4% among controls (p < 0.001). Multivariable logistic regression analysis found that patients with Alzheimer's disease were twice as likely as controls to have had a prior diagnosis of peripheral vestibular disorders, adjusted odds ratio 2.040 (95% confidence interval: 1.829-2.274).

CONCLUSIONS

The findings suggest the possibility of shared or related pathophysiological pathways in Alzheimer's disease and vestibular dysfunction disorders.

LEVEL OF EVIDENCE

3 Laryngoscope, 2024.

Perturbation-based dual task assessment in older adults with mild cognitive impairment

Background

Dual tasking (i.e., concurrent performance of motor and cognitive task) is significantly impaired in older adults with mild cognitive impairment (OAwMCI) compared to cognitively intact older adults (CIOA) and has been associated with increased fall risk. Dual task studies have primarily examined volitionally driven events, and the effects of mild cognitive impairment on reactive balance control (i.e., the ability to recover from unexpected balance threats) are unexplored. We examined the effect of cognitive tasks on reactive balance control in OAwMCI compared to CIOA.

Methods

Adults >55 years were included and completed the Montreal Cognitive Assessment (MoCA) to categorize them as OAwMCI (MoCA: 18-24, n = 15) or CIOA (MoCA: ≥25, n = 15). Both OAwMCI [MoCA: 22.4 (2.2), 65.4 (6.1) years, 3 females] and CIOA [MoCA: 28.4 (1.3), 68.2 (5.5) years, 10 females] responded to large magnitude stance slip-like perturbations alone (single task) and while performing perceptual cognitive tasks targeting the visuomotor domain (target and tracking game). In these tasks, participants rotated their head horizontally to control a motion mouse and catch a falling target (target game) or track a moving object (track). Margin of stability (MOS) and fall outcome (harness load cell >30% body weight) were used to quantify reactive balance control. Cognitive performance was determined using performance error (target) and sum of errors (tracking). A 3 × 2 repeated measures ANOVA examined the effect of group and task on MOS, and generalized estimating equations (GEE) model was used to determine changes in fall outcome between groups and tasks. 2 × 2 repeated measures ANOVAs examined the effect of group and task on cognitive performance.

Results

Compared to CIOA, OAwMCI exhibited significantly deteriorated MOS and greater number of falls during both single task and dual task (p < 0.05), and lower dual task tracking performance (p < 0.01). Compared to single task, both OAwMCI and CIOA exhibited significantly deteriorated perceptual cognitive performance during dual task (p < 0.05); however, no change in MOS or fall outcome between single task and dual task was observed.

Conclusion

Cognitive impairment may diminish the ability to compensate and provide attentional resources demanded by sensory systems to integrate perturbation specific information, resulting in deteriorated ability to recover balance control among OAwMCI.

Aging of the vestibular system and its relationship to dementia

PURPOSE OF REVIEW

Since October 2022, substantial new information has been published on age-related effects on the vestibular system. Since much of this evidence relates to the risk of dementia, the purpose of this review will be to provide an overview of this new information and critically evaluate it.

RECENT FINDINGS

This review will address studies published since October 2022 regarding age-related effects on the vestibular system and their relationship to cognition and dementia. There has been a particular increase in the last year in the number of studies relating aging of the vestibular system to Alzheimer's disease (AD), further supporting the view that vestibular dysfunction is associated with an increased risk of dementia.

SUMMARY

The conclusion of these recent studies is that, consistent with previous studies, vestibular function declines with age, and that this age-related decline is associated with cognitive impairment and an increased risk of dementia. Efforts are being made to consider these implications for cognition in the treatment of vestibular disorders.

Cognition in vestibular disorders: state of the field, challenges, and priorities for the future

Vestibular disorders are prevalent and debilitating conditions of the inner ear and brain which affect balance, coordination, and the integration of multisensory inputs. A growing body of research has linked vestibular disorders to cognitive problems, most notably attention, visuospatial perception, spatial memory, and executive function. However, the mechanistic bases of these cognitive sequelae remain poorly defined, and there is a gap between our theoretical understanding of vestibular cognitive dysfunction, and how best to identify and manage this within clinical practice. This article takes stock of these shortcomings and provides recommendations and priorities for healthcare professionals who assess and treat vestibular disorders, and for researchers developing cognitive models and rehabilitation interventions. We highlight the importance of multidisciplinary collaboration for developing and evaluating clinically relevant theoretical models of vestibular cognition, to advance research and treatment.

Evidence of Vestibular and Balance Dysfunction in Patients With Mild Cognitive Impairment and Alzheimer's Disease

OBJECTIVES

Given the expected rise in dementia prevalence, early diagnosis is vital. As a growing body of literature has identified a potential association between vestibular function and cognition, vestibular assessment may aid in early screening. The aim of the study was to better comprehend the proposed association between vestibular function and Alzheimer's disease (AD) by comparing vestibular parameters (vestibular function testing and clinical balance measures) between a group with mild cognitive impairment (MCI), AD, and healthy controls with age-normal cognition.

DESIGN

Cross-sectional analysis of the GECkO study, an ongoing prospective single-center longitudinal cohort study. This study included 100 older adults (55 to 84 years). A total of 33 participants with MCI, 17 participants with AD, and 50 participants of age, sex, and hearing-matched healthy controls were included.

RESULTS

Participants with AD demonstrated a delayed latency of the p13 component measured by cervical vestibular-evoked myogenic potentials (cVEMP) compared with healthy controls and participants with MCI. Other measures including n23 latency, presence of intact responses, rectified amplitude, mean rectified voltage (measured by cVEMP) and lateral vestibulo-ocular reflex gain (measured by video Head Impulse Test [vHIT]) did not differ between groups. The Timed Up and Go (TUG), Performance-Oriented Mobility Assessment-Balance subscale (POMA-B), and Functional Gait Assessment (FGA) differed significantly between the three groups. Here, more cognitively impaired groups were associated with worse clinical balance scores.

CONCLUSIONS

Vestibular and balance deficits were more prevalent in groups with increasing cognitive decline. Regarding vestibular function testing, p13 latency as measured by cVEMP was delayed in participants with AD. Other cVEMP or vHIT measures did not differ between groups. All three clinical balance assessments (TUG, POMA-B, and FGA) resulted in worse scores along the AD continuum. Future research integrating vestibular parameters that add value (including otolith function testing, balance, and spatial navigation) is recommended to validate the association between vestibular function and cognition while avoiding redundant testing.

Is vestibular function related to human hippocampal volume?

BACKGROUND

Recent studies implicate the effect of vestibular loss on cognitive decline, including hippocampal volume loss. As hippocampal atrophy is an important biomarker of Alzheimer's disease, exploring vestibular dysfunction as a risk factor for dementia and its role in hippocampal atrophy is of interest.

OBJECTIVE

To replicate previous literature on whole-brain and hippocampal volume in semicircular canal dysfunction (bilateral vestibulopathy; BV) and explore the association between otolith function and hippocampal volume.

METHODS

Hippocampal and whole-brain MRI volumes were compared in adults aged between 55 and 83 years. Participants with BV (n = 16) were compared to controls individually matched on age, sex, and hearing status (n = 16). Otolith influence on hippocampal volume in preserved semicircular canal function was evaluated (n = 34).

RESULTS

Whole-brain and targeted hippocampal approaches using volumetric and surface-based measures yielded no significant differences when comparing BV to controls. Binary support vector machines were unable to classify inner ear health status above chance level. Otolith parameters were not associated with hippocampal volume in preserved semicircular canal function.

CONCLUSIONS

No significant differences in whole-brain or hippocampal volume were found when comparing BV participants with healthy controls. Saccular parameters in subjects with preserved semicircular canal function were not associated with hippocampal volume changes.

The static balance ability on soft and hard support surfaces in older adults with mild cognitive impairment

OBJECTIVE

This study aimed to assess the static balance ability of the older adults with mild cognitive impairment (MCI) while standing on soft and hard support surfaces.

METHODS

Forty older adults participated in this study (21 in the MCI group and 19 in the control group). Participants were required to perform balance tests under four conditions of standing: standing on a hard support surface with eyes open, standing on a soft support surface with eyes open, standing on a hard support surface with eyes closed, and standing on a soft support surface with eyes closed. Each test was measured in three trials and each trial lasted 30 seconds. Participants were asked to take off their shoes and place their feet in a parallel position with a 20-centimeter distance for bipedal support. The trajectories of the center of pressure (COP) were measured using a Kistler force platform with a frequency of 1000 Hz to assess balance while standing in both groups, with larger COP trajectories indicating poorer static balance in older adults.

RESULTS

With eyes open, the displacement of COP in the anterior-posterior direction(D-ap) (hard support surface: P = 0.003) and the 95% confidence ellipse area(95%AREA-CE) (soft support surface: P = 0.001, hard support surface: P < 0.001) of the COP in the MCI group standing on hard and soft support surfaces were significantly larger than the control group. The 95%AREA-CE (P < 0.001) of the COP in the MCI group on the soft support surface was significantly larger than on the hard support surface. With eyes closed, the root mean square distance(RDIST), root mean square distance-ML(RDISTml), and 95%AREA-CE of the COP were no significant between-group differences when standing on hard support surfaces. However, the RDIST (P = 0.014), RDISTml (P = 0.014), and 95%AREA-CE (P = 0.001) of the COP in the MCI group on the soft support surfaces were significantly larger than the control group. The 95%AREA-CE (P < 0.001), RDIST (P < 0.001), and RDISTml (P < 0.001) of the COP in the MCI group on the soft support surface were significantly larger than the hard support surface.

CONCLUSION

With eyes open, the older adults with MCI showed poorer static balance ability compared to the older adults with normal cognition on soft and hard support surfaces. With eyes closed, the older adults with MCI showed poorer static balance on soft support surfaces, but no differences on hard support surfaces compared with the older adults with normal cognition. With eyes open and closed, the older adults with MCI showed poorer static balance on soft support surfaces as compared to hard support surfaces.

Relationship between vestibular loss and the risk of dementia using the 2002-2019 national insurance service survey in South Korea

This retrospective cross-sectional study assessed older adults aged between 40 and 80 years, registered in the Korean National Health Insurance Service database from 2002 to 2019 to investigate the association between vestibular loss and the risk of dementia. The population was divided into three groups (general, vestibular loss, and hearing loss). The hazard ratios (HRs) of dementia in the vestibular and hearing loss groups were calculated using national population data. In total, 2,347,610 individuals were identified (general: 2,145,609, vestibular loss: 60,525, hearing loss: 141,476). Mean ages were 53.29 years, 58.26 years, and 58.52 years, respectively. Dementia occurred in 127,081 (IR = 4.91 per 1000 person-years), 7705 (IR = 10.79 per 1000 person-years), and 16,116 (IR = 9.63 per 1000 person-years) patients. The vestibular and hearing loss groups had hazard ratios for dementia of 1.084 (95% CI, 1.059-1.110) and 1.074 (95% CI, 1.056-1.092), respectively, compared with the general group. The results of the current study suggest that vestibular loss increases the risk of developing dementia. Therefore, similar to hearing loss, vestibular loss should be considered a risk factor for dementia, and treatments such as adequate vestibular rehabilitation may reduce this risk.

Association of Bilateral Vestibulopathy With and Without Hearing Loss With Cognitive-Motor Interference

Importance

The past years, evidence suggested that the primary symptoms traditionally associated with bilateral vestibulopathy (BV) do not represent the full picture of this patient population. Recent literature also demonstrated cognitive impairment. However, although multitasking and dual-tasking are widely present in everyday activities, most of these studies assessed cognitive function only in single-task conditions.

Objective

To uncover the association of BV with and without hearing loss with cognitive and motor performance and cognitive-motor interference.

Design, Setting, and Participants

This prospective case-control study assessed persons with an isolated BV and persons with BV and a concomitant hearing loss compared with a healthy control group. Data were analyzed in December 2022. The study was conducted at Ghent University (Ghent, Belgium). Data collection took place between March 26, 2021, and November 29, 2022.

Main Outcomes and Measures

All participants completed the 2BALANCE dual-task protocol, comprising a static and a dynamic motor task that was combined with 5 visual cognitive tasks. These cognitive tasks assessed mental rotation, visuospatial memory, working memory, response inhibition (executive function), and processing speed. All cognitive tasks were performed in a single-task condition (while seated) and in a dual-task condition (combined with a static and a dynamic motor task). The static task comprised balancing on a force platform with foam pad, and the dynamic task comprised walking at a self-selected speed on the GAITRite Walkway. Both motor tasks were performed in the single-task and dual-task condition.

Results

Nineteen persons with BV and hearing loss (mean [SD] age, 56.70 [10.12] years; 10 women [52.6%]), 22 persons with an isolated BV (mean [SD] age, 53.66 [13.35] years; 7 women [31.8%]), and 28 healthy control participants were included (mean [SD] age, 53.73 [12.77] years; 12 women [42.9%]). Both patient groups had mental rotation and working memory impairment in a single-task condition and slower processing speed when walking (ie, during the dynamic dual-task condition). Additionally, the patient group with hearing loss had impaired visuospatial memory and executive function deficits in single-task and dual-task conditions, while this could only be elicited when performing a motor task in persons with isolated BV (ie, when dual-tasking).

Conclusion and Relevance

The findings of this case-control study suggest an association between vestibular function and cognitive and motor performance, even greater in persons with a concomitant hearing loss than in persons with an isolated BV.

Research progress on vestibular dysfunction and visual-spatial cognition in patients with Alzheimer's disease

Alzheimer's disease (AD) or vestibular dysfunction may impair visual-spatial cognitive function. Recent studies have shown that vestibular dysfunction is increasingly common in patients with AD, and patients with AD with vestibular impairment show more visual-spatial cognitive impairment. By exploring the relationship and interaction mechanism among the vestibular system, visual-spatial cognitive ability, and AD, this study aims to provide new insights for the screening, diagnosis, and rehabilitation intervention of patients with AD. In contrast, routine vestibular function tests are particularly important for understanding the vestibular function of patients with AD. The efficacy of vestibular function test as a tool for the early screening of patients with AD must also be further studied. Through the visual-spatial cognitive ability test, the "spatial impairment" subtype of patients with AD, which may be significant in caring for patients with AD to prevent loss and falls, can also be determined. Additionally, the visual-spatial cognitive ability test has great benefits in preventing and alleviating cognitive decline of patients with AD.

Associations of Bilateral Vestibulopathy With Cognition in Older Adults Matched With Healthy Controls for Hearing Status

Question

Is bilateral vestibulopathy (BV) associated with cognitive function in older adults?

Findings

In this cross-sectional study including 34 participants with BV and 34 age-, sex-, and hearing performance–matched controls, participants with BV had worse cognitive function in general, which was most pronounced in the subdomains of immediate memory, visuospatial cognition, and attention.

Meaning

These findings support existing evidence on an association between vestibular loss and cognitive impairment.

Importance

Recent literature suggests there may be a significant effect of the vestibular system on cognition and visuospatial processing. Given the increasing prevalence of dementia and individuals at risk for it, exploring possible modifiable risk factors, including vestibular dysfunction, is vital.

Objectives

To explore the association of bilateral vestibulopathy (BV) with cognitive function in older adults, taking hearing status into account, and to explore multiple vestibular characteristics and their potential associations with cognition in patients with BV.

Design, Setting, and Participants

This cross-sectional study assessed older adults (age 55-84 years) with diagnosed BV from a single center using baseline measurements from the Gehoor, Evenwicht en Cognitie (GECKO) study, an ongoing prospective longitudinal cohort study. Each participant was individually matched with a healthy control based on age, sex, and hearing performance. Data were analyzed in January 2022.

Main Outcomes and Measures

The primary outcome measure was cognition, measured by the Repeatable Battery for the Assessment of Neuropsychological Status for Hearing-Impaired Individuals (RBANS-H).

Results

A total of 68 patients were assessed, including 34 patients with BV (mean [SD] age, 63.3 [6.0] years; 18 [53%] men) matched with 34 control individuals without BV. Overall, participants with BV had a clinically meaningful lower score on the RBANS-H total scale compared with those without BV (mean [SD] score, 98.62 [12.70] vs 105.91 [11.03]). This decline was most pronounced in the subdomains of immediate memory (mean [SD] score, 107.74 [10.66] vs 112.26 [10.66]), visuospatial cognition (mean [SD] score, 90.06 [13.34] vs 100.47 [13.91]), and attention (mean [SD] score, 94.79 [16.39] vs 102.06 [12.97]). There were no differences in language or delayed memory subdomains. Within the BV population, 1 vestibular parameter (the Performance-Oriented Mobility Assessment, in particular the balance subscale) was associated with lower cognitive scores (r₃₂ = 0.51; 95% CI, 0.20 to 0.72; η² = 0.26). Other vestibular parameters, including measurements of the peripheral vestibular end organ and questionnaires, showed no association.

Conclusions and Relevance

These findings suggest there was an association between vestibular loss and cognitive impairment. Further research on the causal mechanisms underlying this association and the possible impact of vestibular rehabilitation on cognition is needed.

Age-Related Changes in the Cochlea and Vestibule: Shared Patterns and Processes

Both age-related hearing loss (ARHL) and age-related loss in vestibular function (ARVL) are prevalent conditions with deleterious consequences on the health and quality of life. Age-related changes in the inner ear are key contributors to both conditions. The auditory and vestibular systems rely on a shared sensory organ - the inner ear - and, like other sensory organs, the inner ear is susceptible to the effects of aging. Despite involvement of the same sensory structure, ARHL and ARVL are often considered separately. Insight essential for the development of improved diagnostics and treatments for both ARHL and ARVL can be gained by careful examination of their shared and unique pathophysiology in the auditory and vestibular end organs of the inner ear. To this end, this review begins by comparing the prevalence patterns of ARHL and ARVL. Next, the normal and age-related changes in the structure and function of the auditory and vestibular end organs are compared. Then, the contributions of various molecular mechanisms, notably inflammaging, oxidative stress, and genetic factors, are evaluated as possible common culprits that interrelate pathophysiology in the cochlea and vestibular end organs as part of ARHL and ARVL. A careful comparison of these changes reveals that the patterns of pathophysiology show similarities but also differences both between the cochlea and vestibular end organs and among the vestibular end organs. Future progress will depend on the development and application of new research strategies and the integrated investigation of ARHL and ARVL using both clinical and animal models.