Subclinical hearing loss may be associated with cognitive impairment
The association between hearing loss and cognition may begin earlier than previously thought — even when patients are still considered to have normal hearing, according to a study published in JAMA Otolaryngology–Head Neck Surgery.
“There has been growing data suggesting that age-related hearing loss is a risk factor for cognitive impairment and dementia,” Justin S. Golub, MD, MS, an assistant professor of otology, neurotology and skull base surgery in the department of otolaryngology-head and neck surgery at Columbia University Vagelos College of Physicians and Surgeons, told Healio Primary Care.
A possible explanation for this association is that poor hearing results in cognitive efforts shifting from making memories to decoding words, Golub said.
He explained that although cognitive impairment is rarely treatable, hearing loss is, and the possibility of treating hearing loss to prevent cognitive decline “represents a potentially exciting lever to manipulate, from a public health standpoint.”
Golub and colleagues conducted a cross-sectional study of 6,451 participants aged 50 years and older from two U.S. epidemiological studies — the Hispanic Community Heath Study (HCHS) and the National Health and Nutrition Examination Study (NHANES).
Among participants, neurocognitive performance was measured by five different tests. Hearing loss was defined as a pure-tone average (PTA) greater than 25 dB, the globally used clinical cutoff for hearing loss.
After finding that the relationship between hearing and cognition appeared to be stronger in those with normal hearing compared with those with hearing loss in a flexible regression technique called generalized additive modeling, Golub and colleagues conducted two separate groups of multivariable linear regressions — one for those with normal hearing (PTA 25 dB or less) and another for those with hearing loss (PTA greater than 25 dB).
Decreased hearing was associated with decreased cognition in adults considered to have normal hearing on all cognitive tests in the HCHS cohort. For instance, hearing drop of 10 dB was associated with a clinically meaningful score decrease on the Digit Symbol Substitution Test. When researchers used a lower threshold to define hearing loss (15 dB), they identified an association with cognition in participants of NHANES with normal hearing.
Researchers found that the relationship between hearing and cognition was as the same or stronger in those considered to have normal hearing compared with those with hearing loss. In combined cohort scores on the Digit Symbol Substitution Test, researchers found that there was a score decrease of 2.28 points (95% CI, 1.56-3) with every 10 dB decrease among those with normal hearing, compared with a 0.97 (95% CI, 0.2-1.75) point decrease in those with hearing loss.
The findings suggest that the current 25 dB threshold to define clinical hearing loss in adults may need to be lowered, according to researchers. In addition, they recommend that studies assessing hearing loss treatment to prevent cognitive impairment and dementia consider using a lower threshold to define hearing loss.
“This new paper suggests that the relationship between hearing and cognition begins earlier than previously recognized,” Golub said. – by Erin Michael
Disclosures: Golub reports receiving travel expenses for industry-sponsored events from Advanced Bionics, Cochlear and Oticon Medical; consulting fees from Auditory Insight, Decibel Therapeutics, Optinose, and Oticon Medical; honoraria from Abbott; and that his department received unrestricted educational grants from Acclarent, Decibel Therapeutics, Storz, Stryker and 3NT. Please see study for all other authors’ relevant financial disclosures.