Importance: Given the rising prevalence of patients with dementia and those at risk for it, early identification is prioritized. As vestibular dysfunction is associated with Alzheimer’s disease (AD) and may contribute to its onset, vestibular assessment may yield an opportunity in early dementia screening. Objective: This systematic review structures and compares the different raw outcome measures used to assess vestibular function while comparing older adults with preserved cognition to individuals with cognitive impairment, either suffering from mild cognitive impairment (MCI) or AD. Design: Two investigators independently and systematically searched publications performing objectively measured vestibular testing in a patient population consisting of either MCI or AD, compared with a control group of older adults with preserved cognition. No limitations regarding language or publication date were applied. References of the retrieved articles were hand searched for relevant articles. Results: Seven articles were included for analysis. A total of 235 older adults with impaired cognition (150 AD, 85 MCI) were compared with a control group of 481 older adults with preserved cognition. Evaluation of the peripheral vestibular function included video head impulse test (vHIT), videonystagmography (VNG), electronystagmography (ENG) including bithermal caloric irrigation and vestibular evoked myogenic potentials (VEMP). The VEMP test, assessing otolith function and the elicited vestibulocollic reflex (VCR), was able to differentiate subjects with AD and its prodromal stage from healthy controls, with p13 latency (p < 0.05) and amplitude (p < 0.05) having the most discriminating power. No correlation between cognitive decline and vestibulo-ocular reflex measurements in different frequency ranges of the semicircular canals (using vHIT, rotatory chair testing, and caloric irrigation) was found. Because of the limited number of available studies and the large heterogeneity in outcome measures, these results have to be interpreted with caution. Conclusions: Measurements of the VCR, as evoked by the VEMP test, discriminate between patients with cognitive impairment (MCI and AD) and older adults with preserved cognition, whereas measurements of the vestibulo-ocular reflex do not. More studies are needed to further elaborate on these findings.

IntroductionDementia is a prevalent disease affecting a growing number of the ageing population. Alzheimer’s disease (AD) is the most common cause of dementia. Previous research investigated the link between hearing loss and cognition, and the effect of vestibular dysfunction on cognition. Hearing loss and, to a lesser extent, vestibular decline both result in a decreasing cognitive function. However, their interaction should not be underestimated. The aim of this study is to assess the effect of hearing loss, vestibular decline and their interaction on cognition in people suffering from mild cognitive impairment (MCI) and dementia due to AD (ADD).Methods and analysisWe designed a prospective longitudinal study to assess the effect of hearing loss and vestibular decline on cognition. A total of 100 cognitively impaired elderly (between 55 and 84 years of age), consisting of 60 patients with MCI due to AD and 40 patients with ADD will be included. The control group will consist of individuals with preserved cognition group-matched based on age, hearing level and vestibular function. A comprehensive assessment is performed at baseline, 12-month and 24-month follow-ups. The primary outcome measure is the change in the Repeatable Battery for the Assessment of Neuropsychological Status adjusted for Hearing-impaired individuals total score, a cognitive test battery assessing different cognitive domains. Secondary outcome measures include additional neuropsychological assessments, cortical auditory-evoked potentials, and evaluation of general and disease-specific health-related quality of life. Variables include cognitive, audiological and vestibular evaluation. Variance analyses will assess the effect of hearing loss and vestibular decline on cognition. More precisely, the link between hearing loss and non-spatial cognitive functioning, the effect of vestibular decline on spatial cognition and the impact of both factors on the rate of conversion from MCI due to AD to ADD will be investigated.Ethics and disseminationThe study protocol was approved by the ethical committee of the Antwerp University Hospital on 4 February 2019 with protocol number B300201938949. The findings will be disseminated through peer-reviewed publications and conference presentations.Trial registration numberClinicalTrials.gov Registry (NCT04385225).

Introduction-Dizziness is considered one of the most common symptoms in general medical practice. Patients can suffer from a wide range of symptoms that are highly relevant while driving and may affect driving ability. In most countries driving restrictions have been suggested for patients with dizziness or a vestibular disorder. However, these restrictions are not always evidence-based and differ significantly between European countries.Objective-The aim of this systematic review was to identify and evaluate studies dealing with driving performance of dizzy patients or patients with a vestibular disorder. Methods-A systematic review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis guidelines. (1) Data sources: PubMed and the reference list of the included articles. (2) Study selection: articles about driving ability and reported driving difficulties in patients with dizziness, or a diagnosed vestibular disorder, were included.(3) Data extraction was performed by two independent authors using predefined data fields: patient's characteristics, diagnostic criteria, sample size, type of evaluation of driving ability and outcome of the study. The protocol (ID 178086) is available online at PROSPERO. Results-Eight out of 705 articles matched the inclusion criteria but varied widely regarding thestudy population, study design and outcome measures. The majority of studies reported a negative impact of dizziness and/or vestibular disorders on self-reported driving ability and car accidents. Yet several studies could not identify any impairment of driving ability.Conclusions Driving ability was negatively affected by dizziness or a vestibular disorder in the majority of included studies with low risk of bias. This systematic review revealed a significant heterogeneity in reporting driving performance and contradictory results. We were therefore unable to identify a causal relationship between dizziness and driving ability. There is a need for prospective studies in populations with different vestibular disorders using subjective and objective outcome measures that have been validated to evaluate driving performance.