Characterizing Variability in Hearing Aid Outcomes in Among Older Adults with Alzheimer's Dementia

This current translational project, funded by NIH, aims to better understand the impact of various signal modification strategies for older adults with Alzheimer's dementia and its potential precursor, known as amnestic mild cognitive impairment. The investigators hypothesize that adults with Alzheimer's dementia represent an extreme case of restricted cognitive ability, such that very low working memory capacity and overall reduced cognitive capacity will limit benefit from advanced signal processing. Thus, the investigators hypothesize that adults with Alzheimer's dementia will receive greater benefit from acoustically simple, high-fidelity hearing aid processing that minimally alters the acoustic signal.

While the advanced signal-processing algorithms used in digital hearing aids have improved average hearing aid benefit and satisfaction, benefit is still highly variable between individual patients, with some individuals reporting much greater benefit than others. The standard approach to selecting signal processing does not consider individual auditory and cognitive differences and how these may be affected by different levels of advanced signal processing. Data provided by the parent grant, R01 DC0012289, indicate that adults with low working memory capacity (a cognitive skill describing ability to process and store information), more hearing loss and/or advanced age receive limited benefit from hearing aid signal processing that substantially modifies the original speech signal. The long term goal of the investigator's research is to optimize choice of signal processing based on individual auditory and cognitive abilities.

The investigators will measure patient outcomes in response to two hearing aid signal processing strategies that represent two clinically common but very different approaches, which differ in the extent of their signal modification. Commercially available hearing aids will be used for this study. The primary patient outcomes for this project are an individual's speech intelligibility and conversation analysis in aided and unaided conditions. Conversation Analysis quantifies conversation breakdowns and repair behaviors as a function of hearing aid signal manipulations and communication partner perceptions of conversation difficulty. Outcome measures will take place after 3-5 weeks of use of each signal modification strategy. The flexibility in timing is to accommodate the scheduling needs of individual participants.

Eligibility Criteria:
Inclusion Criteria:

1. Speak English as their primary language
2. Normal or corrected to normal vision (20/40 binocular vision or unaided using a Snellen chart)
3. Sensorineural hearing loss with pure-tone thresholds 25-70 dB HL at octave frequencies between 500 and 3000 Hz and a 4 frequency (.5, 1, 2, 3 kHz) pure-tone average of greater than or equal to 30 dB in each ear
4. Clinical Dementia Rating (CDR) of 0.5 or 1 (indicating slight or mild cognitive impairment in the areas of memory, orientation, judgment/problem solving, community affairs, behavior at home/hobbies, and personal care)
5. Diagnosis of dementia Alzheimer's type or amnestic mild cognitive impairment (minimum MoCA score of 18).
6. Living at home
7. Minimum Grade 10 education
8. Able to provide own consent as evaluated by the Consent Assessment.

Exclusion Criteria:

1. Clinically significant unstable or progressive medical conditions, or conditions which, in the opinion of the investigator(s) places the participant at unacceptable risk if he or she were to participate in the study
2. History of unresolved communication difficulties following another neurological problem (e.g. stroke or brain tumor), neurodevelopmental disorder (e.g. Down's syndrome), or head/neck cancer
3. Positive history of major psychiatric disorder (e.g. schizophrenia, significant untreated depression)
4. Co-enrolled in other intervention studies targeting hearing, language, or communication strategies
5. Conductive hearing loss pathology, congenital hearing loss, or fluctuating hearing loss
6. Current active hearing aid wearer (defined as wearing hearing aid(s) at least 4 hours a day for most days within the past year)