Genetic and environmental influences on hearing in older women.
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.


CONCLUSIONS
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.
Viljanen
Anne
A
Finnish Centre for Interdisciplinary Gerontology, Department of Health Sciences, University of Jyväskylä, Finland. anne.viljanen@sport.jyu.fi
Era
Pertti
P
Kaprio
Jaakko
J
Pyykkö
Ilmari
I
Koskenvuo
Markku
M
Rantanen
Taina
T
D000368:Aged; D001299:Audiometry; D001309:Auditory Threshold; D015331:Cohort Studies; D004777:Environment; D005260:Female; D006309:Hearing / Q000235:genetics / Q000502:physiology*; D006801:Humans; D007206:Individuality; D008875:Middle Aged; D008957:Models, Genetic; D013067:Speech Perception / Q000502:physiology*; D013069:Speech Reception Threshold Test; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic