Hearing loss is associated with hippocampal atrophy and high cortisol/dehydroepiandrosterone sulphate ratio in older adults
Mitsuhiro Aoki, Hiroshi Okuda, Hiromasa Ishihara, Hisamitsu Hayashi, Toshimitsu Ohashi, Takesumi Nishihori, Bunya Kuze
Abstract
Objectives Hearing loss (HL) has been recognised as a prodromal symptom of cognitive disorder with aging. It is still uncertain if HL leads to cognitive impairment directly or through an indirect mechanism.Design Participants of this study underwent an auditory test, blood tests, and brain MRI. The atrophy rate of the hippocampus (HP) was calculated using voxel-based specific areas. A partial correlation analysis whilst controlling for the effect of age was performed to analyse the factors affecting hearing levels and HP atrophy rate (HP%).Study sample Thirty-six older adults with hearing impairmentResults The group of participants with moderate or severe HL (n = 22) had higher cortisol/dehydroepiandrosterone sulphate (C/D) ratio, geriatric depression score (GDS) and HP% than the mild HL or normal hearing group (n = 14, p < 0.05). The HP% showed a significant positive correlation with the C/D ratio, GDS and the hearing level of high frequency (HF) (p < 0.05). The C/D ratio was positively correlated with the HP% and the hearing level of the HF (p < 0.05).Conclusions Our results suggest that the HL is associated with the atrophy of HP and high C/D ratios in older adults; however, HL may not be causally related to hippocampal atrophy.