Hearing across the lifespan by mouse models of Alzheimer’s disease

Although hearing loss and dementias, such as Alzheimer’s Disease (AD), are known to be closely linked, the exact nature of the link has not yet been determined. To better understand the association, we have been measuring hearing across the lifespan by several mouse models of AD. Using behavioral operant conditioning techniques, male and female mice are trained to nose poke for a chocolate milk reinforcer when they hear a 14 kHz pure tone. Using psychophysical signal detection theory, d-prime thresholds are calculated daily for each mouse subject from about 100 days of age through two years of age. Thresholds for several AD models and their wild-type counterparts generally increase across the lifespan as the mice get older. Although there is some variability across mouse subjects, thresholds from the AD models and wild-type controls are similar across the lifespan. Thus, although older humans with AD are more prone to hearing loss than those without AD, the current mouse models of AD do not recapitulate this phenotype. These results suggest an opportunity to investigate other factors contributing to the heterogeneity in hearing across the lifespan in mouse models of AD. [Work supported by NIH AG081747.]