We conducted a prospective study on older adults needing support, who did not have mild cognitive impairment (MCI), to examine the relationship between hearing loss at baseline and development of either cognitive decline or MCI one year later.
Data were collected at baseline and after one year. Tests used were pure tone audiometry, a cognitive impairment screening test, and a self-administered questionnaire. Hearing loss of the subjects was assessed and categorized according to the side with better hearing, and they were divided into 40 dB or lower (no or mild impairment), and 41 dB or higher (moderate to severe impairment) groups. We defined cognitive decline as a decrease in one point or more from baseline in the follow-up cognitive impairment screening test after one year and MCI was defined based on the criteria of the cognitive impairment screening test. Logistic regression analysis was performed with cognitive decline or development of MCI as the dependent variable, and variables that were shown to be associated with hearing loss in χ 2 tests (p<0.1) as the independent variables, to calculate the odds ratio (OR) for cognitive decline or development of MCI.
Of the 34 subjects, 21 (62%) had no or mild hearing impairment and 13 (38%) had moderate to severe hearing impairment at baseline. In the follow-up study after one year, cognitive decline was confirmed in 18 subjects (53%) and MCI in 10 subjects (29%).
Subjects with moderate to severe hearing impairment at baseline had an OR of 6.67 (95%CI : 0.92-48.18) of developing cognitive decline one year later, compared to subjects with no or mild hearing impairment, which was marginally significant. No associations were observed with development of MCI.
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