Short summary

Hearing loss has been consistently associated with an increased risk of dementia and cognitive impairment. Additionally, a clinical-relevant link between hearing loss and accelerated cognitive decline has been found, indicating a great potential for prevention through the use of hearing aids and other auditory function rehabilitation methods. Despite this growing body of evidence, the nature of this relationship and the underlying mechanisms are not well understood. This project aims to fill in this knowledge gap by using the unique high-quality Danish registers to generate a study population consisting of all residents in the region of Southern Denmark.

Rationale

Several potential mechanisms linking hearing loss and cognitive impairment have been previously proposed in the literature, such as: 1) hearing loss demands extensive cognitive load, possibly reallocating cortical resources that can be used for other brain activities (e.g. memory); 2) hearing loss leads to social isolation and depression, which are well-known risk factors for dementia; 3) there is a common underlying cause to both outcomes. However, whether these mechanisms are inter-connected and whether there is a true causal relationship between hearing loss and cognitive function are questions that need to be investigated. 

Considering these potential pathways, a better understanding of the mechanisms behind the observed association between hearing loss and dementia is important. Better understanding this relationship is a critical step for the implementation of health care policies and the development of prevention and rehabilitations strategies, where both social consequences and economic costs should be considered. Therefore, this project is aimed at answering many different research questions regarding this topic, such as:

• Does hearing loss increase the risk for dementia?

• Does traffic noise increase the risk for both hearing problems, including tinnitus, as well as dementia?

• Does the use of auditory function rehabilitation methods (e.g. hearing aids) reduce the risk for dementia?

• Is there an economic benefit from the use of hearing aids and other auditory function rehabilitation methods, through mitigating and/or postponing symptoms of cognitive impairment?

Description of the cohort

Cohort is composed by all older adults (> 50 years old) living in the region of Southern Denmark in the period between 1998 and 2017

Data and biological material

Data from the ongoing database called AuditBase, which includes all hearing examinations made in the public system on the region of Southern Denmark from 1998 until now. 

Data from national health-registries such as the Danish National Patient Register, the Danish National Prescription Registry, the Danish Psychiatric Central Register, among others.

Collaborating researchers and departments

Department of ORL Head and Neck Surgery and Audiology, Odense University Hospital

• Consultant, M.D. PhD, Associate Professor, Jesper Hvass Schimidt

The Maersk Mc-Kinney Moller Institute, University of Southern Denmark

• Assistant Professor, Ellen Raben Pedersen, PhD

Department of Clinical Research, University of Southern Denmark

• Postdoctoral researcher, Manuella Lech Cantuaria, PhD

Department of Environment and Cancer, the Danish Cancer Society

• Senior scientist, Mette Sørensen, PhD