SummaryDementia, with Alzheimer’s disease as the most prevalent form, is one of the most frequent diseases in our aging society with no effective treatment to date. Therefore, research has focused on prevention strategies and discovered several modifiable risk factors for dementia in the last years. According to a recent report, hearing loss is the largest potentially modifiable risk factor, accounting for 8% of attributable risk for dementia in the population. Hearing loss is a public health problem affecting more than 466 million people worldwide and becomes more common with age. Previous research provided evidence for a relationship between hearing loss and dementia as well as cognitive impairment. In addition, hearing loss has been associated with poorer brain health in older adults, including magnetic resonance imaging (MRI) derived brain atrophy and reduced white matter microstructural integrity. However, the causality as well as the mechanisms underlying the association of hearing loss with dementia/cognition remains unclear to date, and studies investigating the association of hearing loss with brain health are still sparse. Moreover, the use of conventional hearing aids seems to diminish or at least curtail the risk of cognitive impairment and incident dementia. However, the underlying mechanisms linking hearing aid use to lower dementia risk and better cognitive function also remain unclear. Hearing loss is often accompanied by a decline in other senses, including vision and olfaction. Evidence exists that the co-occurrence of hearing, vision, and/or olfactory impairment is associated with a higher risk of cognitive decline and dementia compared to individuals with only one sense impaired. However, the mechanistic pathways still remain to be fully elucidated. Therefore, the present study aims to first provide a comprehensive assessment on the association of hearing loss and cognitive function by focusing on changes in brain structure as a possible mechanistic pathway. The assessment of brain health will include grey and white matter changes, thus spanning the range from neurodegenerative to vascular pathologies. In addition, the study will shed more light on the hitherto understudied association between the use of hearing aids and cognitive function, and on the mechanisms, particularly at the brain level, underlying those association. Second, the study will investigate the association between impairments in multiple sensory domains (i.e., hearing, vision, and olfaction) and cognitive function as well as brain health.

Keywords brain-health cognition dementia hearing-aids hearing-loss hearing-treatment magnetic-resonance-imaging olfactory-impairment sensory-deprivation structural-brain-measures visual-impairment white-matter-hyperintensities

InstitutionsUniversitätsmedizin Greifswald, Klinik für Hals-, Nasen- und Ohrenheilkunde, Universität Münster, Klinik für Neurologie, Universitätsmedizin Greifswald, Institut für Epidemiologie der Universität Münster, Universitätsklinikum Bonn, Forschungszentrum Jülich