A large-scale study spanning 33 countries has found that the use of hearing aids helps reduce the likelihood of developing dementia. The more effective the treatment, the lower the risk of the disease.

Hearing loss affects 70–90% of people aged 85 and older. About 7% of age-related hearing impairments are accompanied by cognitive disorders. Hearing aids are commonly used to correct hearing loss, but their effectiveness is often questioned.

The study, published in Cell Reports Medicine, analyzed data from 61,089 older adults with hearing impairments across 33 countries. In countries with middle incomes, participants tended to be younger than those in high-income countries. Only 15.4% of respondents reported using a hearing aid. The highest proportion of users was found in Denmark, while the lowest was in China. Switzerland recorded the highest effectiveness of hearing aids, and China the lowest.

Over an average follow-up period of 6.5 years, signs of dementia appeared in 14.6% of participants. The use of hearing aids was associated with a 9% average reduction in the risk of cognitive impairment among all participants, including those who experienced only slight improvement. In middle-income countries, the risk reduction reached 24%.

The link between hearing aid use and reduced dementia risk persisted even after excluding the first three years of observation, although the statistical significance of this effect was lost in high-income countries. A more pronounced risk reduction was observed among women under 70, individuals with lower education levels, and those who were unmarried.

The effectiveness of hearing aids played a particularly important role. Among those who reported significant improvement in hearing, the incidence of dementia dropped by 14% compared to those who did not use hearing aids. For participants who noted low treatment effectiveness, no risk reduction was observed.

In high-income countries, a decrease in risk was seen only among users of highly effective hearing aids. In middle-income countries, hearing aid use in general was linked to a lower risk of dementia, but there was insufficient data on their effectiveness for statistical conclusions. Thus, confirmed risk reduction is mainly associated with high-quality hearing aids.

Successful rehabilitation for hearing loss requires not only providing a hearing aid, but also informing patients about the consequences of untreated hearing loss and ensuring the equipment is of proper quality.