Evaluation of hearing levels and vestibular function and the impact on cognitive performance in (pre)-symptomatic patients with DFNA9: protocol for a prospective longitudinal study (Rosetta study)

Introduction: Untreated hearing loss is the largest potentially modifiable risk factor for dementia. Additionally, vestibular dysfunction has been put forward as a potential risk factor for accelerated cognitive decline. Patients with Deafness Autosomal Dominant 9 (DFNA9) present with progressive sensorineural hearing loss and bilateral vestibulopathy and show significantly worse results in cognitive performance compared with a cognitively healthy control group. This highlights the need for adequate treatment to prevent further cognitive decline. This study aims to determine how hearing and vestibular function evolve in (pre-)symptomatic carriers of the p.Pro51Ser mutation in the COCH gene and how this impacts their cognitive performance and health-related quality of life.

Methods and analysis: A prospective, longitudinal evaluation of hearing, vestibular function and cognitive performance will be acquired at baseline, 1-year and 2-year follow-up. A total of 40 patients with DFNA9 will be included in the study. The study will be a single-centre study performed at the ORL department at the Antwerp University Hospital (UZA), Belgium. The control group will encompass cognitively healthy subjects, already recruited through the GECkO study. The primary outcome measure will be the Repeatable Battery for the Assessment of Neuropsychological Status adjusted for the Hearing-Impaired total score. Secondary outcome measures include Cortical Auditory-Evoked Potentials, vestibular assessments and health-related quality of life questionnaires. The expected outcomes will aid in the development of gene therapy by providing insight in the optimal time window for the application of gene therapy for the inner ear.

Ethics and dissemination: The ethical committee of UZA approved the study protocol on 19 December 2022 (protocol number B3002022000170). All participants have to give written initial informed consent in accordance with the Declaration of Helsinki. Results will be disseminated to the public through conference presentations, lectures and peer-reviewed scientific publications.