Hearing Loss Linked with Increased Risk of Dementia

Manuella Lech Cantuaria, PhD

Credit: ResearchGate

Hearing loss is associated with an increased risk of dementia, but hearing aids are linked with reducing the risk, according to a new study.¹

According to previous research, current risk factors of dementia are physical inactivity, smoking, diet—but hearing loss serves as another suggested risk. While hearing loss has been suggested as a risk factor for dementia, little high-quality research explored the association.

Studies examining hearing loss and dementia had been cross-sectional with conclusions on temporality and causality with different adjustment strategies and definitions of hearing loss and dementia. Prior longitudinal studies produced either no or week associations. A study tracking 639 adults for 12 years found mild hearing loss doubled dementia risk, moderate loss tripled risk, and severe loss made individuals 5 times more likely to develop dementia.²

A new study, led by Manuella Lech Cantuaria, PhD, from the University of Southern Denmark, aimed at evaluating the link between hearing loss and onset dementia—and how a hearing aid affects the association.¹

The cohort study, conducted in Southern Denmark between January 2003 and December 2017, was comprised of 573,088 participants ≥ 50 years old who did not have dementia prior to baseline. Mean age was 60.8 years old. The team measured hearing status based on the Hearing Examinations in Southern Denmark database, containing all pure-tone audiometry examinations conducted at public hearing rehabilitation clinics in Southern Denmark.

Of the 573,088 participants, 23,023 had dementia after a median follow-up of 10 years (range: 0.25 – 15.0). Many of the participants who developed dementia were older, men, retired, and had a lower income and education level.

A hearing loss was linked to an increased risk of dementia (adjusted hazard ratio [HR]: 1.07; 95% CI, 1.04 – 1.11), after adjusting for age, sex, calendar year, cohabiting status, education, income, country of origin, occupational status, presence of cardiometabolic disease, and area-level socioeconomic variables. Also, severe hearing loss in the better ((HR: 1.20; 95% CI, 1.09 – 1.32) and worse (HR: 1.13; 95% CI, 1.06 – 1.20) ear was associated with a higher dementia risk, compared to no hearing loss in the other ear.

“We found that [hearing loss] was associated with a 7% higher risk of dementia, which is a lower increase in risk than observed in most longitudinal studies,” the investigators wrote.

The link between hearing loss and Alzheimer disease was stronger than for overall dementia. Though, only mild hearing loss was linked to a higher Alzheimer risk. After censoring individuals at 80 years old, the findings showed stronger associations between dementia and hearing loss.

“A potential explanation for this pattern is that people who get a diagnosis of [hearing loss] at younger ages are more likely to have [hearing loss] that is caused by hereditary factors,” the investigators wrote. “These patients are likely to have lived with their [hearing loss] for years, which may have affected their cognition for a longer period and during a stage of life when listening can have a higher effect in daily activities (eg, work routine and a more intense social life).”

Moreover, having hearing aids was associated with a lower risk of dementia. The risk of dementia was higher among people with hearing loss who did not use hearing aids (HR: 1.20; 95% CI, 1.13 – 1.27) than people with hearing loss who used hearing aids (HR: 1.06; 95% CI, 1.01 – 1.10).

“We found that among people with a diagnosis of [hearing loss], [adjusted hazard ratios] among hearing aid users were substantially lower compared with people not using hearing aids, which suggests that hearing aid use could be a tool in preventing or delaying dementia,” the investigators concluded.

^References

1. ^{Cantuaria, M. Pedersen, E, Waldorff, F. Hearing Loss, Hearing Aid Use, and Risk of Dementia in Older Adults. JAMA Otolaryngol Head Neck surg. 2024. doi:10.1001/jamaoto.2023.3509.}
2. ^{The Hidden Risks of Hearing Loss. Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-hidden-risks-of-hearing-loss#:~:text=In%20a%20study%20that%20tracked,more%20likely%20to%20develop%20dementia.Accessed January 4, 2024.}