Objectives: Hearing impairment
(HI) in midlife may increase the risk of dementia. However, epidemiological research on the association between HI and mild cognitive impairment
(MCI) is very limited.
The present cross-sectional study
investigated the relationship between HI and MCI using baseline data from the Aidai Cohort Study. Study subjects were 995 Japanese
adults aged 36 to 84 years. We used the audiometric definition of HI adopted by the World Health Organization, which identifies the speech-frequency pure-tone average hearing thresholds at 0.5, 1, 2, and 4 kHz tones. HI was defined as present when pure-tone average was >25 dB HL in the better hearing ear. MCI was defined as being present when a subject had a Japanese
version of the Montreal Cognitive Assessment score of <26. Adjustment was made for age, sex, smoking status, alcohol consumption, leisure time physical activity, hypertension, dyslipidemia, diabetes mellitus, history of depression, body mass index, waist circumference, employment, education, and household income.
Among the 995 study subjects, the prevalence values of HI and MCI were 24.3% and 44.5%, respectively. HI was independently positively associated with MCI: the multivariate-adjusted odds ratio (95% confidence interval) was 1.86 (1.32 to 2.62). HI was independently related to a higher prevalence of MCI in those aged 60 to 69 years and those aged 70 years or older: the multivariate-adjusted odds ratios (95% confidence intervals) were 1.64 (1.03 to 2.62) and 2.30 (1.04 to 5.27), respectively.
HI may be associated with a higher prevalence of MCI.