公衆衛生

Hearing loss is a risk factor for dementia, but dementia subtypes underlying this association and effect modifiers are unclear. Here we examined the association of hearing loss with all cause dementia, Alzheimer's disease and vascular dementia, and effect modifiers of this association in the Framingham Study.

Framingham Study participants >60 years, who underwent Pure Tone Audiometry at the 15^th biennial exam (1977-1979), and had subsequent dementia surveillance for up to 40 years were included. We defined hearing loss as pure-tone average (0.5-4.0 kHz) > 25 dB in the better ear and used National Health and Aging Trends Study (NHATS) categories: normal (range: 0 - 25dB), mild hearing loss (range: 26 - 40dB), moderate to severe hearing loss (>40dB). All cause dementia diagnosed using DSM IV criteria, Alzheimer's disease diagnosed using National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA) criteria, vascular dementia diagnosed using the National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (NINDS-AIREN) NINDS- AIREN criteria.

Among 2000 participants (mean age 69.5 years (IQR 60.04-88.74), 60% women, followed for up to four decades, we identified 633 participants with new onset dementia. Moderate to severe hearing loss was associated with 30% increased risk of dementia (Alzheimer's disease HR 1.27 [95%CI 0.99-1.62] p = .06; vascular dementia: HR 1.7[CI 1.06-2.59] p = .027). Age stratified analysis revealed the effect was restricted to persons aged <70 years at hearing assessment (all cause dementia: HR 1.56[CI 1.19-2.05] p = .001; Alzheimer's disease: HR 1.46[CI 1.07-2.0] p = .017; vascular dementia: HR 2.08[CI 1.22-3.56] p = .007) and strongest in APOE-ε4 carriers (all cause dementia (ε4 positive: HR 2.99 [CI 1.77-5.06] p = < .0001, ε4 negative: HR 1.16 [CI 0.85-1.58] p = 0.36); Alzheimer's disease (ε4 positive: HR 3.44 [CI 1.92-6.17] p = < .0001, ε4 negative: HR 1.09 [CI 0.78-1.54] p = .64)).

Hearing loss is associated with increased risk of all cause dementia, Alzheimer's disease and vascular dementia among Framingham Study participants, with greatest risk in those aged <70 years and in APOE-ε4 carriers. Screening for and managing hearing loss starting in mid-life might reduce dementia risk.