The AGES-Reykjavik Study is examining genetic susceptibility and gene/environment interaction as these contribute to phenotypes common in old age, including hearing loss. The NIDCD funding of the hearing component and balance questionnaires for this study will support audiometric examinations consisting of otoscopy, acoustic immittance (bilateral tympanometry and ipsilateral acoustic reflexes), and pure-tone, air-conduction audiometry to determine hearing thresholds in each ear at 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz. Through a prior Interagency Agreement with the National Institute on Aging (NIA), NIDCD funded hearing exams on about 5,200 subjects, aged 67 to 93 years in the Age, Gene/Environment Susceptibility; Reykjavik (AGES/Reykjavik I) in Reykjavik, Iceland from 2001 through 2006. Subsequently, AGES?Reykjavik II, 2007?2010 (approximately 3,500 surviving subjects), was funded by NIA and co-sponsoring ICs (NIDCD, NEI, and NINDS) to conduct longitudinal follow-up exams. With NIDCD funding, questions have been asked about use of hearing aids, subjective evaluation of hearing acuity including the Gallaudet scale, tinnitus (frequency and duration), ear diseases and operations, and other factors related to hearing. Questions were also added in AGES-RS II, 2007?2010, regarding specific dizziness/balance and falling problems that study participants had experienced (since AGES I) or currently. In order to examine broad genetic effects, first-degree relatives have been identified in the existing AGES data (i.e., siblings and parent-child combinations). Second-degree relatives or more distant cousins can also be identified. Further investigation of the genetics of hearing loss will be accomplished through participation in a broad genome scan for associations with defined phenotypes, including age-related hearing loss defined on the basis of results in AGES I. Additional follow-up studies of hearing status and balance/dizziness questions were performed in 2012 on a younger, randomly-selected AGES offspring cohort (n=500) and, in 2013, this offspring sample will be augmented with approximately 400 younger offspring subjects who, based on their parents? genotypes and exam results (phenotypes) are at very high risk of developing Alzheimer?s. These subjects will also be tested for hearing loss and balance/dizziness questionnaire responses will be obtained. Other measures collected throughout on AGES subjects and their offspring include brain imaging, detailed vision exams, and many other assessments. Available covariates include: age, gender, education, weight at midlife, weight change from midlife, smoking history, physical activity, quadriceps strength and hand grip strength (determined by Isometric dynamometry), co-morbid conditions, hospitalization in previous 5 years, CRP, fasting glucose, and glomerular filtration rate or GFR (adjusted for body mass index [BMI]).
