The contribution of cardiovascular disease (CVD) to the development of sensorineural hearing loss (SNHL) is not well understood. The cochlea is known to be very sensitive to ischemia. Distortion product otoacoustic emissions (DPOAEs) can determine cochlear loss in SNHL and studies have demonstrated abnormal DPOAEs prior to the development of a detectable hearing loss in subjects with CVD. Hypertension (HTN) and CVD in the Afro-American population in Mississippi (MS) is the highest in the nation. The Jackson Heart study (JHS) is a population-based cohort study underway in Jackson, MS, to examine this. We predict a relationship between the incidence and severity of CVD and the development of SNHL. We hypothesize that SNHL will be correlated with the presence of uncontrolled hypertension and diabetes. We also hypothesize that cochlear dysfunction may be an early finding in the progression of CVD prior to events such as stroke. We will test our hypothesis by integrating an on-site, pure-tone, central processing and DPOAE hearing screen protocol into the JHS.
Specific Aim 1 : Perform a cross-sectional examination of the JHS cohort to characterize the prevalence of hearing loss in this population.
Aim 1. 1 Determine the prevalence of middle ear disease by otoscopy, bone conduction audiometry, and tympanometry.
Aim 1. 2 Determine the prevalence of SNHL.
Aim 1. 3 Correlate frequency specific DPOAEs with pure-tone thresholds (PTT) to create a distortion product audiogram. The rate of change with age of DPOAEs and of PTT will be compared to assess the possible presence of strial presbycusis in order to estimate the etiology of SNHL.
Aim 2 : Using the prevalence of SNHL from Aim 1, we will calculate the relative risk of hearing loss in relation to the careful evaluation of the JHS cohort for traditional (Aim 2.1) and non-traditional (Aim 2.2) cardiovascular disease risk factors. We propose to enroll 3,137 Afro-American men and women aged 21-95 during the 5 year grant period. From these participants, a cohort with normal hearing will be recruited for a prospective study of the association between hearing loss and incident vascular events. Hearing investigators will be blinded to the CVD status of the subjects during the study period. This study will be the first population-based examination of SNHL and central processing disorders in African Americans. Using the data on CVD gathered by the JHS, we hope to better describe the pathogenesis of SNHL, and its relationship to stroke and CVD.
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