BMI over the lifecourse and hearing ability at age 45 years: a population based study

Abstract

Previous research on anthropometric factors and adult hearing loss has found relationships, in separate studies, to birthweight and contemporary BMI. However no study has examined data on BMI over the lifecourse. This paper uses data from the 1958 British Birth Cohort to examine relationships between BMI (both in childhood and adulthood), changes in BMI between adjacent age waves, and hearing thresholds at 1 kHz and 4 kHz obtained by audiometric examination at age 45 yrs. Body Mass Index (BMI) in adulthood, but not in childhood, was associated with increased hearing threshold levels at both 1 kHz and 4 kHz at age 45yrs. Two further models examine the effect of changes in BMI between successive waves and adult hearing thresholds, firstly adjusting for childhood hearing loss and a range of further childhood factors (including birthweight, family history of hearing loss, mother’s weight, childhood social class) and secondly adjusting in addition for noise, current social class, current systolic blood pressure and diabetes, current smoking and drinking. In the first model, increases in BMI at age intervals throughout the lifecourse, over both childhood and adulthood, were independently associated with increased hearing threshold levels at both frequencies in mid-life, largest relationships being shown at both frequencies to increasing BMI in adolescence and in early adulthood. These relationships generally persisted in the second model, though were reduced more at earlier ages (pre 23 yrs). Noise at work attenuates the relationship between BMI change and mid life hearing threshold, more so at 4 kHz than at 1 kHz and for BMI change at older ages.