SELF-REPORTED HEARING LOSS, COGNITIVE PERFORMANCE, AND RISK OF MCI: FINDINGS FROM THE WISCONSIN REGISTRY FOR ALZHEIMER’S PREVENTION

Abstract

Auditory deficits are present in Alzheimer's disease dementia (AD) but it remains largely unknown whether they precede or are concomitant with the disease. The aim of this study was to determine the prevalence of hearing loss in a cohort of middle-aged adults at risk for AD, and evaluate whether hearing loss is associated with prospective cognitive decline and progression to mild cognitive impairment (MCI). Seven hundred and eighty-three cognitively-normal adults (age=53.55±6.52 years, 71% women, and 42% with maternal history of AD) enrolled in the Wisconsin Registry for Alzheimer's Prevention participated in this study. Participants underwent serial cognitive and clinical assessments and self-reported whether they had ever been diagnosed with hearing loss as part of a medical history questionnaire. Diagnosis of MCI was rendered via a multidisciplinary consensus conference. Frequency distribution was used to assess prevalence of hearing loss. Covariate-adjusted linear regression was used to assess the relationship between hearing loss at initial assessment and cognitive performance at a subsequent visit four years later. Binary logistic regression was used to estimate risk of incident MCI as a function of prior hearing loss, after controlling for relevant covariates. 72 (9.20%) participants reported having a diagnosed hearing loss whereas 711 (90.80%) participants reported having normal hearing. Relative to those who reported normal hearing, individuals who reported hearing loss scored significantly poorer on tests of processing speed and set switching (Trail Making Test parts A&B, p=.046 and .025, respectively), cognitive flexibility (Stroop Color-Word Interference, p=.014), psychomotor speed (WAIS-R Digit Symbol Substitution Test, p=.012) and a composite measure of Speed and Flexibility (p=.030) four years later. The odds of being characterized as having MCI at the latter visit were over three times higher for those who had reported hearing loss at the initial or intermediate visits (mean time interval=2.50±.47 years), relative to those who had not (OR=3.26 p=.047, 95% CI 1.02–10.44). In this cognitively-normal, at-risk cohort, self-reported hearing loss was prospectively associated with poorer cognitive performance and increased incidence of progression to MCI. Identification and treatment of hearing loss might be a viable approach to forestall the public health crisis posed by AD.