Peripheral hearing and cognition: Evidence from the staying keen in later life (SKILL) study

Research has increasingly suggested a consistent relationship between peripheral hearing and selected measures of cognition in older adults. However, other studies yield conflicting findings. The primary purpose of the present study was to further elucidate the relationship between peripheral hearing and three domains of cognition and one measure of global cognitive status. It was hypothesized that peripheral hearing loss would be significantly associated with poorer performance across measures of cognition, even after adjusting for documented risk factors. No study to date has examined the relationship between peripheral hearing and such an extensive array of cognitive measures. Design: Eight hundred ninety-four older adult participants from the Staying Keen in Later Life study cohort were eligible, agreed to participate, and completed the baseline evaluation. Inclusion criteria were minimal to include a sample of older adults with a wide range of sensory and cognitive abilities. Multiple linear regression analyses were conducted to evaluate the extent to which peripheral hearing predicted performance on a global measure of cognitive status, as well as multiple cognitive measures in the domains of speed of processing (Digit Symbol Substitution and Copy, Trail Making Test Part A, Letter and Pattern Comparison, and Useful Field of View), executive function (Trail Making Test Part B and Stroop Color-Word Interference Task), and memory (Digit Span, Spatial Span, and Hopkins Verbal Learning Test). Results: Peripheral hearing, measured as the three-frequency pure-tone average (PTA) in the better ear, accounted for a significant, but minimal, amount of the variance in measures of speed of processing, executive function, and memory, as well as global cognitive status. Alternative measures of hearing (i.e., three-frequency PTAs in the right and left ears and a bilateral, six-frequency PTA [three frequencies per ear]) yielded similar findings across measures of cognition and did not alter the study outcomes in any meaningful way. Conclusions: Consistent with literature suggesting a significant relationship between peripheral hearing and cognition, and in agreement with our hypothesis, peripheral hearing was significantly related to 10 of 11 measures of cognition that assessed processing speed, executive function, or memory, as well as global cognitive status. Although evidence, including the present results, suggests a relationship between peripheral hearing and cognition, little is known about the underlying mechanisms. Examination of these mechanisms is a critical need to direct appropriate treatment.