NIH Research Festival
Hearing impairment (HI) in midlife (ages 45-65) may be associated with long-term neurodegeneration of temporal lobe structures, which show early pathology in Alzheimer’s disease (AD). HI, as measured by the pure tone average between 1990 and 1994, was investigated as a predictor of MRI-based temporal volume loss, measured from 2008 to 2015, in 194 Baltimore Longitudinal Study of Aging participants (mean follow-up time of 19.3 years). Linear mixed effects models were used to examine the association of HI with longitudinal MRI-based measures of temporal lobe structures in addition to global and lobar regions, adjusting for baseline demographic characteristics (age, sex, cognitive status, education), intracranial volume, and vascular burden. As an exploratory analysis, we compared temporal lobe volume loss between HI in right and left ears. Poorer mid-life hearing was associated with volumetric declines in the right hippocampus and left entorhinal cortex. Poorer mid-life hearing in the right ear was associated with steeper volumetric declines in right cerebellum, right middle temporal gyrus, bilateral entorhinal cortex, and left parahippocampal gyrus. Poorer mid-life hearing in both right and left ears was associated with steeper declines in right hippocampus as well as bilateral ventricular enlargement. Poorer mid-life hearing could be a risk factor for volumetric decline in temporal lobe structures affected by AD. Laterality of poorer mid-life hearing may affect temporal lobe structural volumes, indicating diminished right ear dominance.
Scientific Focus Area: Neuroscience
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