A large-scale French study has found that even mild hearing loss could be associated with a 10% increase in the odds of cognitive impairment. The study, conducted in middle-aged adults, also reported that hearing aid use may not significantly reduce cognitive impairment in this population.
In the study, published in JAMA Network Open, investigators analyzed data from 62,072 participants aged 45 to 69 years with a mean age of 57.4 years (standard deviation [SD] = 7 years), 52% of whom were women. The cross-sectional analysis, part of the CONSTANCES cohort, objectively measured hearing loss through pure-tone audiometry, which assesses air-conduction thresholds at specific frequencies. Mild hearing loss was defined as a pure-tone average (PTA) greater than 20 dB, and disabling hearing loss was defined as PTA over 35 dB.
Among the study participants, 38% of them had mild hearing loss, 10% had disabling hearing loss, and 3% used hearing aids. The investigators found that mild hearing loss was associated with a 10% increase in the risk of global cognitive impairment (odds ratio [OR] = 1.10, 95% confidence interval [CI] = 1.05–1.15), and disabling hearing loss was linked to a 24% increase in risk (OR = 1.24, 95% CI = 1.16–1.33). However, the risk of cognitive impairment did not significantly differ between hearing aid users and participants with disabling hearing loss who did not use hearing aids (OR = 0.94, 95% CI = 0.83–1.07).
Notably, among the participants with depression, hearing aid use was associated with a lower risk of cognitive impairment (OR = 0.62, 95% CI = 0.44–0.88), suggesting a possible protective effect in this subgroup.
The proportion of participants with global cognitive impairment increased with the severity of hearing loss: 16% among those with normal hearing, 27% among those with mild hearing loss, and 37% among those with disabling hearing loss (P < .001 for trend). This association persisted across different cognitive tests, including the Digit Symbol Substitution Test (DSST), Free and Cued Selective Reminding Test (FCSRT), and the Trail Making Tests (TMT-A and TMT-B). A global cognitive score was created using principal component analysis of these test results.
The study used several methods, including propensity score adjustments, matching, and inverse probability of treatment weighting, to assess whether hearing aids could reduce the risk of cognitive impairment. None of these methods found a significant benefit of hearing aids in the general population. However, hearing aids were associated with reduced cognitive impairment among those with depression, a finding that could reflect a synergistic effect of hearing and mood interventions.
The study is one of the largest of its kind, using objective measures of hearing and cognition to establish a robust link between hearing loss and cognitive impairment. The investigators noted that prior studies relied on self-reported hearing data, which can be inaccurate.
Despite its strengths, the cross-sectional design limited the ability to infer causality between hearing loss and cognitive decline. Additionally, hearing and cognitive tests were conducted at the same time, and data on the duration and frequency of hearing aid use were not available. Moreover, the study population was predominantly White, which could limit generalizability to other racial and ethnic groups.
The authors declared having no competing interests.
