Large-scale studies on the development of age-related hearing loss (ARHL) have identified several conditions that often co-occur with ARHL, such as falls and cognitive decline. Yet the relationship between such risk factors and the onset of ARHL is unclear. A forthcoming article in the Journals of Gerontology suggests that impaired cognitive function and hypertension may predict increased decline in hearing.
Because ARHL can contribute to a decreased quality of life, and because it is associated with a variety of other disorders, it is important to know more about factors that influence the onset. Greater knowledge on the relationship between hearing loss and cognitive decline, for example, may lead to improved preventive strategies for both conditions, as well as improved understanding of how they both occur.
Researchers used data from two large-scale longitudinal studies on the health of middle aged and older adults in Australia. A total of 4,221 participants were administered comprehensive hearing measures at multiple time points over 11 years. Participants were also administered a blood pressure exam and a cognitive exam, in addition to a questionnaire on medical conditions, smoking history, workplace noise exposure, and demographic information. The choice of the medical, cognitive, and personal history items was based on earlier research indicating that these domains are possible risk factors for hearing loss.
As would be expected based on previous knowledge of ARHL, within this sample hearing loss in low-range frequencies occurred later than loss in high-range frequencies, and accelerated with age. At 75 years of age, ARHL for those frequencies needed to hear speech increased at a rate of 0.91 decibels per year. Overall, men in the sample began to experience mild hearing impairment at a mean age of 67.8 years, while women did so at a mean age of 71.1 years. Women had faster decline than men in high- and mid-range frequencies. Men had a faster rate of decline in hearing, as well, but this sex difference disappeared when controlling for demographic and health variables.
The only factors that predicted accelerated ARHL in the sample were hypertension and cognitive impairment. This is a useful finding in light of multiple studies associating hearing loss with cognitive impairment, which have led to the hypothesis that hearing loss leads to cognitive decline. It may still be the case that hearing loss can lead to cognitive decline, but there may be an underlying factor (such as a neurological pathology) that leads to both. The fact that cognitive impairment predicts loss of hearing in low- and mid-range frequencies is useful for future research on the pathways between ARHL and cognitive decline.
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