Association of plasma adiponectin levels with hearing thresholds in adults.

OBJECTIVE: Obesity is an independent risk factor for age-related hearing impairment. Adiponectin is one of the major adipocytokines secreted by adipose tissue. The aim of our study was to examine whether there is an association between plasma adiponectin concentrations and hearing sensitivity in adults. DESIGN AND METHODS: We recruited 954 adults aged 40-86 years, with normal or symmetrical sensorineural hearing loss and normal cognitive function. Backward stepwise multivariate linear regression was performed to assess the association between plasma adiponectin concentrations and hearing level Z-scores. Further, backward stepwise logistic regression analysis was performed to determine the risk of hearing impairment by plasma adiponectin concentration.
RESULTS: Adiponectin concentrations were lower, and waist circumference (WC) was higher in subjects with Z-high in the upper 50% of Z-high. Z-high (correlation coefficient: β = -0·02; standard error [SE] = 0·01; P = 0·003), but not Z-middle or Z-low, was significantly associated with plasma adiponectin concentrations after adjusting for WC, systemic diseases, smoking and alcohol consumption. The risk of hearing impairment for high frequencies, but not low or middle frequencies, decreased by 0·97-fold (odds ratio ± SE = 0·97 ± 0·02, P = 0·048, 95% confidence interval = 0·93-1·00) for every 1-unit increase in adiponectin concentration, after adjusting for age, gender, WC, systemic diseases, smoking and alcohol consumption.
CONCLUSION: Plasma adiponectin may protect peripheral hearing function, particularly that related to high frequencies. Adiponectin may be a mediator of obesity-associated, age-related hearing impairment.