Patients with risk factors for dementia, such as diabetes and hypertension, experienced a 48% slowing of cognitive decline after wearing a hearing aid for 3 years, results of the first randomized trial of its kind show.
Results of the ACHIEVE study add to growing evidence that addressing hearing impairment may be a critically important global public health target to prevent dementia.
"These results provide compelling evidence that treating hearing loss is a powerful tool to protect cognitive function in later life, and possibly over the long term, delay a dementia diagnosis," principal investigator Frank Lin of Johns Hopkins University School of Medicine and the Bloomberg School of Public Health, said in a press release.
However, he added, "Any cognitive benefits of treating age-related hearing loss are likely to vary depending on an individuals' risk of cognitive decline."
The findings were presented at the Alzheimer's Association International Conference (AAIC) 2023 and were simultaneously published online July 17 in The Lancet.
A Common Condition
Age-related hearing loss is extremely common, affecting two thirds of adults older than 60. It is treatable with hearing aids and audiologic support services. Previous observational studies suggested that correcting hearing impairment might reduce cognitive decline and dementia.
However, the investigators point out that such research is often limited by residual confounding and lack of information about the duration and characteristics of the hearing loss correction.
To provide more robust evidence of the value of hearing aids in preserving cognition, the investigators conducted the ACHIEVE study, a randomized trial that included 977 adults aged 70–84 years with untreated hearing loss who were free from substantial cognitive impairment in four communities across the US.
Participants were recruited from two populations at each site ― older adults participating in the ongoing Atherosclerosis Risk in Communities (ARIC) study, which is aimed at understanding cardiovascular and cognitive health, and healthy volunteers from the same communities who were generally healthier than the ARIC participants and who served as the de novo cohort.
At baseline, study participants were similar with respect to hearing (pure tone average dB of 39.4) and were free of substantial cognitive impairment.
However, compared to de novo participants, the participants from ARIC were more likely to be older, female, Black, to live alone, to have less education and lower income, and to be more likely to have diabetes and hypertension.
Researchers randomly assigned all participants to either a hearing intervention group or an aging health education control group.
Those in the hearing intervention group completed four 1-hour sessions with an audiologist every 1–3 weeks, received bilateral hearing aids fitted to prescriptive targets, were regularly updated on the use of the devices, and learned hearing rehabilitative strategies.
The control intervention was designed to match the intensity of the hearing intervention. Participants met regularly with a certified health educator who administered the 10 Keys to Healthy Aging, an interactive health education program for adults aged 65 years.
The primary endpoint was change at year 3 in a global cognition standardized factor score derived from a comprehensive neurocognitive battery administered annually. Tests included delayed word recall, digit symbol substitution, incidental learning, trail making parts A and B, logical memory, digit span backwards, Boston naming, word fluency, and animal naming.
In the total study population, the global cognitive change did not differ significantly between the hearing and health education groups (difference, 0.002; 95% CI, –0.077 to 0.081; P = .96).
However, among the ARIC cohort, there was a significant 48% reduction in the hearing aid group compared to the control group (difference, 0.191; 95% CI, 0.022 – 0.360; P = .027). In the de novo cohort, cognitive change did not differ significantly between the two groups.
There were no between-group differences in the combined cohort for the secondary cognitive outcomes of change in executive function, language, and memory.
In the ARIC cohort, the hearing intervention was significantly associated with a slower decline in language compared to controls (P = .012). In addition, there were no unexpected adverse events related to study participation.
The study findings support previous research showing that treating hearing loss in older adults should be added to existing national dementia risk-reduction strategies, the investigators note.
A follow-up study of the ACHIEVE cohort is underway to study longer-term effects of hearing intervention on cognition and other outcomes.
The underlying mechanisms between untreated hearing loss and cognitive decline remain unclear, but there are several hypotheses. Hearing impairment may make the brain work harder, which could have a negative effect on cognition, or it may accelerate brain atrophy. Another possibility is that people with hearing loss become less socially engaged, and the lack of stimulation may result in brain atrophy.
A limitation of the study was that it could not be blinded, which may have biased results. Also, two of the 10 tests in the neurocognitive battery contained only auditory stimuli, and controls with untreated hearing loss might not have performed as well on these measures if they didn't correctly understand the auditory stimuli.
Commenting for Medscape Medical News, Percy Griffin, PhD, director of scientific engagement, Alzheimer's Association, said the results are "encouraging" and warrant further investigation.
"Although the trial was ultimately not as positive as investigators might have hoped, it's starting to give us some clues on some subpopulations that need to be followed up on."
Hearing is important for enjoying everyday activities, not just for cognition, said Griffin.
However, he noted the study addressed only one aspect of behavior/lifestyle (hearing impairment). "We need to address several different aspects, and we need bigger, more representative studies."
The study was funded by the US National Institutes of Health. Lin reports research grants from the US National Institutes of Health and Eleanor Schwartz Charitable Foundation; consulting fees from Frequency Therapeutics and Apple; payment for expert testimony and participation on a scientific advisory board for Fondation Pour L'Audition and Sharper Sense; being a volunteer board member for Access HEARS; donation in-kind from Sonova/Phonak to Johns Hopkins University for hearing technologies used in the study; and being the director of a public health research center funded in part by a philanthropic donation from Cochlear to the Johns Hopkins Bloomberg School of Public Health.
Alzheimer's Association International Conference (AAIC) 2023: Presented July 18, 2023.
Lancet. Published online July 17, 2023. Abstract
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Cite this: New Evidence Hearing Aids Help Slow Cognitive Decline - Medscape - Jul 18, 2023.