medwireNews: People with hearing loss (HL) may be at an increased risk for developing incident dementia, with additional risk in those people who do not use hearing aids, finds a study published in JAMA Otolaryngology–Head & Neck Surgery.
“The Lancet commission on dementia prevention ranked HL as the most important modifiable risk factor for dementia due to its elevated prevalence and high pooled risk estimates,” explain Manuella Lech Cantuaria (University of Southern Denmark, Odense) and colleagues.
They note that “[m]ost existing studies on HL and dementia/cognition are cross-sectional, precluding conclusions on temporality and causality,” while the few longitudinal studies have shown high variability in the strength of an association.
Cantuaria et al therefore conducted a large population-based cohort study between 2003 and 2017 of 573,088 participants (52% women) aged 50 years or older (median 61 years) who had lived in Southern Denmark for at least the past 5 years and did not have dementia at baseline.
They reviewed data from national registries on the hearing status, based on pure-tone audiometry examinations, and hearing aid requests or fittings for these individuals, and assessed for incident dementia over a mean follow-up of 8.6 years.
During follow-up, there were 23,023 cases of dementia, and the risk among the 41,014 participants with HL (>20 decibels hearing level [dBHL] for pure-tone averages at any frequency) was increased by 7%, compared with the 470,667 participants without HL. For the 61,317 individuals with suspected HL (those without hearing data in the Hearing Examinations of Southern Denmark database) the risk for dementia was increased by 3%.
These risks were determined after considering confounding factors such as patient demographics, comorbidities, and individual and area socioeconomic status.
Cantuaria and team point out that “mainly severe HL seemed to be associated with a higher dementia risk,” reporting increased risks of 20% and 13% for severe HL (>60 dBHL) in the better ear and worse ear, respectively, compared with no HL in the corresponding ear. This finding also supports their hypothesis that “the better ear hearing ability would best predict how HL affects a patient’s life in different social and cognitively demanding situations.”
When assessing dementia outcome types, the researchers found stronger associations between both HL and suspected HL with Alzheimer’s disease compared with overall dementia, although this increased risk was only significant among individuals with mild HL (26–40 dBHL), at 18% compared with no HL.
When the risk for dementia was assessed according to age at diagnosis, participants younger than 80 years with HL had a significant 17% greater risk for dementia than their similarly aged peers without HL, which increased to a significant 30% higher for those with severe HL in the better ear. Cantuaria and co-authors suggest that this is most likely due to the HL being caused by hereditary factors and an earlier onset, “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.”
Cantuaria et al also report a significant 20% higher risk for dementia associated with HL versus no HL in people who did not use hearing aids, compared with a marginally significant 6% increased risk in those who did.
This suggests that “hearing aids might prevent or delay the onset and progression of dementia,” they say, adding that, if proven in further studies, this may explain the generally lower risk estimates in this study compared with earlier studies, since “Denmark is the European country with the highest proportion of hearing aid users among those with self-reported HL.”
Cantuaria and team conclude that their findings highlight a need “for a better understanding of the association between HL and dementia as a critical step for the development of prevention strategies.”
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JAMA Otolaryngol Head Neck Surg, January 2024; doi:10.1001/jamaoto.2023.3509