No abstract

Our findings indicate that vestibular impairment is associated with increased risk of cognitive and psychiatric comorbidity. The vestibular system is anatomically connected with widespread regions of the cerebral cortex, hippocampus and amygdala. Loss of vestibular inputs may lead to impairment of these cognitive and affective circuits. Further longitudinal research is required to determine if these associations are causal.

Objective Recent studies suggest an association between vestibular and cognitive function. The goal of the study was to investigate whether vestibular function was impaired in individuals with mild cognitive impairment (MCI) and Alzheimer’s disease (AD) compared to cognitively normal individuals. Study Design Cross-sectional study. Setting Outpatient memory clinic and longitudinal observational study unit. Patients Older individuals ≥ 55 years with MCI or AD. Age, gender and education-matched normal controls were drawn from the Baltimore Longitudinal Study of Aging (BLSA). Intervention Saccular and utricular function was assessed with cervical and ocular vestibular-evoked myogenic potentials (c- and oVEMPs) respectively, and horizontal semicircular canal function was assessed with video head impulse testing. Main Outcome Measures Presence or absence of VEMP responses, VEMP amplitude and vestibular ocular reflex (VOR) gain were measured. Results Forty-seven individuals with cognitive impairment (MCI N=15 and AD N=32) underwent testing and were matched with 94 controls. In adjusted analyses, bilaterally absent cVEMPs were associated with an over three-fold odds of AD (OR 3.42, 95% CI 1.33–8.91, p=0.011). One microvolt increases in both cVEMP and oVEMP amplitudes were associated with decreased odds of AD (OR 0.28, 95% CI 0.09–0.93, p=0.038 and OR 0.92, 95% CI 0.85–0.99, p=0.036, respectively). There was no significant difference in VOR gain between the groups. Conclusions These findings confirm and extend emerging evidence of an association between vestibular dysfunction and cognitive impairment. Further investigation is needed to determine the causal direction for the link between peripheral vestibular loss and cognitive impairment.

This study suggests that vestibular dysfunction partially mediates the association between age and cognitive impairment. Moreover, the cognitive impairment that results from vestibular loss may contribute to ADL difficulty and falls in older individuals.