Association Between Nonoptimal Blood Pressure and Cochlear Function
By Rachael R. Baiduc, Ph.D.
High blood pressure (BP) is a common chronic condition in the United States with an estimated prevalence among adults of 31 percent, or 69 million. In addition to an increased risk of stroke and heart disease, elevated BP may also increase risk of hearing loss. In fact, the two commonly co-occur. Numerous studies have evaluated the association between hearing loss and risk factors for cardiovascular disease, including high BP. However, data from population- and laboratory-based studies remain inconclusive, and most prior work has focused on the effects of BP level on behavioral responses to sounds.
Contrary to the team’s hypothesis, subtle blood pressure elevation was not associated with poorer hearing or cochlear dysfunction. A greater elevation in BP (that is, hypertension itself) may be associated with more pronounced effects on inner ear function, warranting further investigation.
Our study published in Ear and Hearing in August 2020 extended previous work by examining the effect of BP on auditory status using extended high-frequency audiometry (which measures behavioral responses to sound) and distortion product otoacoustic emissions (DPOAEs), a noninvasive, objective test of inner ear (cochlear) function. Sixty individuals took part in this study and underwent a health assessment in addition to comprehensive audiological testing.
Participants were placed into one of two groups according to their BP level: “optimal” (systolic/diastolic BP <120/<80mm Hg) or “nonoptimal” (systolic ≥120 or diastolic ≥80mm Hg, or the use of antihypertensives).
Initial findings suggest significant correlations between diastolic BP and behavioral hearing thresholds. We also identified a correlation between diastolic BP and DPOAE levels in the mid-frequency range. However, more in-depth statistical analysis indicated that other factors such as age and gender are more important drivers of impaired auditory function than BP level.
Contrary to our hypothesis, we found that subtle BP elevation was not associated with poorer hearing or cochlear dysfunction. A greater elevation in BP (that is, hypertension itself) may be associated with more pronounced effects on inner ear function, warranting further investigation. In addition, our study suggests that DPOAEs may be a viable tool to characterize the relationship between risk factors for heart disease (and in particular, stage 2 hypertension) and hearing health. Follow-up investigations are underway.
A 2018 ERG scientist, Rachael R. Baiduc, Ph.D., is an assistant professor in the department of speech, language, and hearing sciences at the University of Colorado Boulder, where she is also the director of the Hearing Epidemiology and Research Diagnostics (HEARD) Laboratory.