Dynamics of electrophysiology and morphology in older adults with age-related hearing loss

Abstract

Age-related hearing loss (presbycusis) is a highly prevalent disease and can have a severe negative impact on social interactions, and eventually on the quality of life of the people affected. It is therefore of the utmost importance to find biomarkers from which to evaluate presbycusis. Studying presbycusis comprehensively constitutes a complex undertaking because hearing problems are frequently reported by older adults whose hearing impairment has failed to be identified through the traditional assessment of hearing loss, in which such impairment is viewed as a phenomenon occurring at the auditory periphery only. This PhD thesis is among the first to report behavioral consequences and biomarkers of hearing and speech processing problems in older adults which occur independently of peripheral hearing loss. This PhD thesis provides new insights into auditory perceptual difficulties in older adults and their most common treatment. It extends present frameworks of age- related hearing loss by suitably combining EEG, structural MRI and behavior. The results of the experimental work done in this PhD thesis have several implications: first, novel hearing tests assessing multifactorial aspects of hearing loss, especially central hearing loss, should be implemented in clinics; second, central hearing loss emerges as a function of age-related changes in the morphology and functional lateralization of the auditory areas of the brain; third, peripheral hearing impairment delays central auditory plasticity, which suggests that preventive treatment is the key to understanding speech into old age; and fourth, hearing aids are indispensable for rehabilitation, but clinics need to inform older adults that the hearing aid type and algorithm can only be evaluated after intensive hearing aid usage, across 12 weeks for approximately 12 hours a day. Finally, the fact that hearing aids mainly focus on peripheral hearing treatment points to the necessity for new rehabilitation ideas. It is hoped that the accumulated findings of this PhD thesis will open the door for such novel innovation.