Hearing loss is an established independent risk factor for dementia. Likewise, recent research demonstrated cognitive deficits in subjects with vestibular loss. However, in these studies data have not been adjusted for the hearing status of the enrolled study subjects. As hearing loss prevalence is high in patients with vestibular loss, this could be a major confounder. Therefore, in this study the investigators investigate cognition in patients with bilateral vestibulopathy with and without hearing loss. The investigators adjust data for the hearing status of the patients to explore the link between hearing loss, vestibular loss and cognition.

Inclusion criteria for BVP patients were:

1. Bilaterally reduced vestibular function, as defined by the Bárány Criteria for BVP (Michael Strupp 2017):

   • horizontal angular VOR gain < 0.6 measured by the vHIT, and/or
   • reduced caloric response (sum of bithermal, 30° and 44°, max. peak slow phase velocity (SPV) on each side < 6°/sec), and/or
   • reduced horizontal angular VOR gain < 0.1 upon sinusoidal stimulation on a rotatory chair. At our clinic rotatory chair tests are performed using sinusoidal rotation (0.05 Hertz) with a peak velocity of 60°/sec (Van der Stappen A 2000).

2. Disease duration of BVP > 6 months.

Healthy controls (HC). Only subjects with no history of vertigo, scores <5 on the Dizziness Handicap Inventory (DHI) and normal hearing thresholds at 0.25 - 8 kHz, based on age and sex (defined by the BS 6951:1988, EN 27029:1991 and ISO 7029-1984 standards), were enrolled in the study.

For both BVP patients and HC the following additional inclusion criteria were applied: 1) Age ≥ 18 years; 2) Fluency in Dutch; 3) No history of neurological diseases (e.g. dementia, Parkinson's disease, cerebrovascular accident, etc.); 4) Absence of clinical signs indicating dementia or mild cognitive impairment.

Patients with bilateral vestibulopathy, which was confirmed by vestibular testing, were enrolled in the patient group. Healthy controls with normal hearing and vestibular system were used to compare cognitive outcome measures with. Correction were made for age, sex, education and computer usage.