Genetic and Environmental Influences on Hearing in Older Women

Abstract

Background. This study examined the relative contribution of genetic and environmental effects on the air-conducted hearing threshold level (0.5–4 kHz) and speech recognition threshold level of the better ear as well as self-reported hearing in older women. Methods. Hearing was measured as a part of the Finnish Twin Study on Aging in 103 monozygotic (MZ) and 114 dizygotic (DZ) female twin pairs aged 63–76 years. Audiometric measured hearing was tested using standardized methods in soundproof conditions. Self-reported hearing was assessed by a structured question. Quantitative genetic modeling was used for data analyses. Results. No significant differences in age, exposure to noise, hearing-aid use, auditory diseases or accidents, or number of self-reported chronic conditions or prescription medicines were observed between the MZ and DZ twins. A genetic component in common accounted for 75% (95% confidence interval [CI], 67%–81%) of the variance in the better ear's hearing threshold level and 54% (95% CI, 43%–64%) in the better ear's speech recognition threshold level, according to a bivariate genetic analysis. In addition, 10% (95% CI, 4%–15%) of the variance in the better ear's speech recognition threshold level was explained by its specific genetic component. Conclusion. Individual differences in audiometrically measured air-conducted hearing threshold level (0.5–4 kHz) and speech recognition threshold level in the better ear were largely accounted for by genetic differences between individuals. In contrast, self-reported hearing appears to be accounted for solely by environmental factors.