Vestibulo-ocular reflex in patients with amnestic mild cognitive impairment and normal controls: a comparative study

Several studies have shown the anatomical associations between the vestibular system and cognitive processes, especially spatial memory. One of the first problems that occur in Alzheimer's disease (AD) is spatial memory deficits. The preclinical stage of AD is mild cognitive impairment (MCI). Amnestic type of MCI (aMCI) is more likely to progress to AD. Previous studies have demonstrated high incidence of vestibular disorders in AD patients; however, the balance system of aMCI patients has not been investigated. Therefore, the present study aimed to investigate vestibulo-ocular reflex (VOR) impairments in aMCI patients compared with control group.
In this cross-sectional study VOR gain and catch-up saccades in six semicircular canals were measured in 12 aMCI patients and 12 normal controls using video head impulse test.
Vestibulo-ocular reflex gains in direction of all vertical semicircular canals were lower in aMCI- compared with normal-group (right anterior canal 0.74±0.17 vs 0.87±0.12; right posterior canal 0.77±0.10 vs 0.90±0.10; left anterior canal 0.87±0.10 vs 0.97±0.11; left posterior 0.72±0.18 vs 0.87±0.90). Catch-up saccades were found in direction of all canals in aMCI patients while there were no saccades in normal groups.
In aMCI patients there was more vestibular dysfunction, which might be associated with cognitive deficits especially spatial type. In brief, vestibular investigation is suggested in aMCI patients.