Summary It is well known that Alzheimer's disease (AD) and hearing loss often occur together. What is unknown, however, is the relationship between noise exposures and patients with AD. Our goal with this supplement is to examine the link between noise exposure, age, listening environment (noise or quiet), and sex in transgenic mouse models of AD compared to wild-type mice. In our one Specific Aim, we will behaviorally measure auditory acuity before and after noise exposures in the above groups of mice and the two listening environments to determine if young AD mutants are more susceptible to noise exposure than young wild-type mice, and to examine the differences of the susceptibility to noise in quiet and noise environments. In our parent grant, we have been measuring the effects of noise on hearing in young and old, male and female mice, and have found that old mice suffer greater hearing loss post-noise exposure than young mice when listening in quiet environments, but not in noisy environments. This supplement will utilize the same techniques in two mouse models of AD to determine if young AD mice act like old wild-type mice in terms of susceptibility to hearing loss following acoustic trauma. Although these mouse models are commonly used to study the anatomical correlates of AD, we are only beginning to comprehend the functional implications of AD on hearing, especially hearing in noise, and these experiments will help us better understand how aging, sex, and noise all play a role in the communication problems faced by patients with AD.

Project Narrative The proposed experiments address the gaps in our knowledge about harmful noise exposures on hearing in quiet and noise, sex differences in hearing, and the effects of age on hearing in mouse models of Alzheimer's disease. There is a known link between hearing loss and Alzheimer's disease, and learning more about the nature of the link in mouse models, studied using behavioral methodologies in awake and trained mice, will greatly increase the awareness of such factors on Alzheimer's disease.