Lin FR, Metter EJ, O’Brien RJ, Resnick SM, Zonderman AB, Ferrucci L.
Department of Otolaryngology-Head and Neck Surgery, The Johns Hopkins School of Medicine, JHOC 6120, 601 N Caroline St, Baltimore, MD 21287. flin1@jhmi.edu.
Abstract
OBJECTIVE: To determine whether hearing loss is associated with incident all-cause dementia and Alzheimer disease (AD).
DESIGN: Prospective study of 639 individuals who underwent audiometric testing and were dementia free in 1990 to 1994. Hearing loss was defined by a pure-tone average of hearing thresholds at 0.5, 1, 2, and 4 kHz in the better-hearing ear (normal, <25 dB [n = 455]; mild loss, 25-40 dB [n = 125]; moderate loss, 41-70 dB [n = 53]; and severe loss, >70 dB [n = 6]). Diagnosis of incident dementia was made by consensus diagnostic conference. Cox proportional hazards models were used to model time to incident dementia according to severity of hearing loss and were adjusted for age, sex, race, education, diabetes mellitus, smoking, and hypertension.
SETTING: Baltimore Longitudinal Study of Aging.
PARTICIPANTS: Six hundred thirty-nine individuals aged 36 to 90 years. Main Outcome Measure  Incident caces of all-cause dementia and AD until May 31, 2008.
RESULTS: During a median follow-up of 11.9 years, 58 cases of incident all-cause dementia were diagnosed, of which 37 cases were AD. The risk of incident all-cause dementia increased log linearly with the severity of baseline hearing loss (1.27 per 10-dB loss; 95% confidence interval, 1.06-1.50). Compared with normal hearing, the hazard ratio (95% confidence interval) for incident all-cause dementia was 1.89 (1.00-3.58) for mild hearing loss, 3.00 (1.43-6.30) for moderate hearing loss, and 4.94 (1.09-22.40) for severe hearing loss. The risk of incident AD also increased with baseline hearing loss (1.20 per 10 dB of hearing loss) but with a wider confidence interval (0.94-1.53).
CONCLUSIONS: Hearing loss is independently associated with incident all-cause dementia. Whether hearing loss is a marker for early-stage dementia or is actually a modifiable risk factor for dementia deserves further study

Nash SD, Cruickshanks KJ, Klein R, Klein BE, Nieto FJ, Huang GH, Pankow JS, Tweed TS.
R. Klein, and B. E. K. Klein), University of Wisconsin School of Medicine and Public Health, and Department of Communicative Disorders, University of Wisconsin (Mr Tweed), Madison; Institute of Statistics, National Chiao Tung University, Hsinchu, Taiwan, Republic of China (Dr Huang); and Division of Epidemiology and Community Health, University of Minnesota School of Public Health, Minneapolis (Dr Pankow).
Abstract
OBJECTIVE: To estimate the prevalence of hearing impairment (HI) and evaluate the cross-sectional associations of environmental and cardiovascular disease risk factors and HI in middle-aged adults.
DESIGN: Data were collected as part of the Beaver Dam Offspring Study, an epidemiological cohort study of aging. Hearing impairment was defined as a pure-tone average (0.5, 1.0, 2.0, and 4.0 kHz) greater than 25 db hearing level in either ear. Word recognition in competing message (WRCM) was measured using the Northwestern University No. 6 word list. Questionnaire information about behaviors, environmental factors, and medical history was also collected.
PARTICIPANTS: The participants (N = 3285) were offspring of participants of the population-based Epidemiology of Hearing Loss Study and ranged in age from 21 to 84 years (mean age, 49 years).
RESULTS: The prevalence of HI was 14.1%, and the mean (SD) WRCM score was 64% (15%). In a multivariate model, after age, sex, education, and occupational noise were controlled for, a history of ear surgery (odds ratio [OR], 4.11; 95% confidence interval [CI], 2.37-7.15), a larger central retinal venular equivalent (OR, 1.77; 95% CI, 1.20-2.60 [fourth quartile vs first quartile]), and a higher hematocrit percentage (OR, 0.77; 95% CI, 0.63-0.95 [per 5%]) were independently associated with HI. Factors associated with lower WRCM scores were similar but also included mean intima-media thickness (mean difference, -0.63%; 95% CI, -1.06% to -0.19%; P = .005 [per 0.1 mm]) and statin use (mean difference, -2.09%; 95% CI, -3.58% to -0.60%; P = .005).
CONCLUSIONS: Hearing impairment is a common condition in middle-aged adults. Cardiovascular disease risk factors may be important correlates of age-related auditory dysfunction

Allison D. Brown, Carly A. McMorris, R. Stewart Longman, Richard Leigh, Michael D. Hill, Christine M. Friedenreich and Marc J. Poulina

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