Vestibular evoked myogenic potentials: early predictors of Alzheimer's disease?

Recent studies have reported connections between vestibular function and cognition and also reported more prevalence of vestibular impairment in patients with Alzheimer's disease. Because patients with amnestic mild cognitive impairment (aMCI) are more likely to develop Alzheimer's disease, this study was conducted to evaluate vestibular dysfunction of otolith organs in aMCI patients compared to normal subjects.
In our case-control study, 11 patients (22 ears) with aMCI with mean age of 56.73±8.83 years and 11 normal participants (22 ears) with mean age of 54.30±7.4 years were eva­luated for ocular and cervical vestibular evoked myogenic potentials (o- and cVEMP). Occurrence of VEMP responses, amplitude, latency and threshold of these waves were recorded and compared between the two groups.
Ocular VEMP was absent in 63.6% of aMCI patients and in 18.2% of the normal group. The difference was significant (p=0.002), while occurrence rate, amplitude, latencies and threshold of cVEMP were not significantly different between the two groups (p>0.05). McNemar's test showed that there was no significant relationship between occurrences of two potentials in aMCI group.
These findings show the presence of vestibular dysfunction, especially in the pathways of ocular vestibular evoked potential, in patients with amnestic mild cognitive impairment. Given that previous studies have shown that cVEMP was absent in Alzheimer's disease, absence of oVEMP can be used as an indicator for predicting future impairment in individuals with amnestic MCI.