Cognition Effects of Hearing Aids and Auditory Training in Older Age

Background:

Sensorineural hearing loss is the most common sensory deficit among older adults. There is no clinically proven method to predict the onset of this condition, as its occurrence is generally slow and progressive, affecting both ears equally. Recent studies have documented that hearing loss in older adults is independently associated with reduced cognitive functioning, mood and social interaction, and that hearing aid use and auditory training could improve cognitive abilities, social, emotional, psychological, and physical well-being of people. Despite the high prevalence of hearing loss in older adults, and the consequences for health outcomes, people are generally slow to acquire hearing aids, and almost two-thirds of older adults with hearing impairment do not use hearing aids. The popularity of auditory training has also declined in recent years and the focus of research has been shifted to only improving wearable amplification such as hearing aids. No research has been designed to specifically look at the effect of both hearing aid use coupled with auditory training on cognitive performance in older adults.

Study aim:

The aim of the current study is to investigate the impact of hearing aid use coupled with auditory training on mood, social relationships and cognitive functioning in a crossover intervention trial.

Study hypothesis:

The rationale for this study objective is based on the following hypotheses:

H1: In older adults with sensorineural hearing loss, hearing aids in combination with auditory training will be more effective for improving cognition than auditory training on its own.

H2: In older adults with sensorineural hearing loss, hearing aids in combination with auditory training will be more effective for improving mood and social interaction than auditory training on its own.

Crossover design:

This is a randomised crossover trial with a total of 40 participants randomized into two equal groups (20 each) to carry out separate crossover experiments. All participants will undergo individualised auditory training for a period of 6 months, and will be randomly allocated to one of the following groups.

1. Participants who will be fitted with hearing aids only for the first 3 months of the auditory training program - Group A
2. Participants who will be fitted with hearing aids only for the last 3 months of the auditory training program - Group B Participants will be tested at baseline, and at three and six months in terms of cognition, mood and social engagement. The primary outcome measure will be changes in cognitive performance as measured by the Swinburne University Computerized Assessment Battery (SUCCAB). Secondary outcome measures will include changes in mood and social engagement scores.

Setting of the study This study is set in Victoria, Australia. It will be conducted in independent living aged care facilities across Melbourne. These residents live in their own unit or similar accommodation, and are generally capable of caring for themselves in all aspects of daily living. In addition, elderly participants from the Swinburne University of Technology's Centre for Human Psychopharmacology (CHP) database who live independently will be recruited to take part in the study.

Recruitment:

Independent living aged care facilities will be contacted by telephone to explain the study. If an aged care facility shows interest in the study, researchers will visit the facility to provide the facility manager with more detailed written and oral information. If the facility manager consents for their facility to participate in the study, the study will be advertised at the facility and flyers will be distributed to all the residents inviting them to an information session. Participants from the Swinburne University of Technology's CHP database will be contacted by telephone and email to explain the study and participants who express interest will be invited to attend an information session. At the information session, researchers will explain the purpose and significance of the study. At the same time, a pre-selection screening will be conducted to identify participants who are cognitively healthy, likely to benefit from hearing rehabilitation, and who will be able to participate in the cognition battery testing (reasonable sight and not colour blind). Selected participants will be sent a Participant Information and Consent Form package that includes detailed information on the study procedure, a consent form and a return pre-paid envelope. Once written consent is received, participants will be invited to complete baseline measures and to confirm their eligibility before enrolment into the study.

Participants:

The baseline cohort will consist of forty (40) older adults with either a mild or moderate symmetric sensorineural hearing loss. All participants will be first time hearing aid users, having never worn hearing aids previously. Participants will be screened for adequate cognitive functioning using the Mini-mental state examination (MMSE). Participants must have a global cognitive impairment as determined by a score greater than 24 on the (MMSE).

Sample size:

Power analyses were conducted to determine the sample size required. Previous research and the results of the power analysis suggest that a total sample size of 36 is sufficient to detect a moderate size effect (f=0.25), with power of 80% and a significance level of 5%. Therefore, a total sample size of 40 participants will be recruited to provide a definitive test of the hypotheses, while allowing for 10% attrition.

Data collection methods:

The assessments selected for this study are categorized as:

1. Hearing Assessments

• Otoscopy and tympanometry: Following otoscopy, all participants will undergo tympanometry and acoustic reflex testing to assess the status of the middle ear.
• Pure tone audiometry in each ear: To understand the degree of hearing impairment, hearing ability will be measured at threshold frequencies 0.5, 1, 2, 3, 4, 6 kHz in both ears. An online Speech Perception Test will be used in addition to the standard audiograms for the purpose of measuring hearing loss and hearing aid fitting.

1. Paper-based Questionnaire

Participants will complete a paper-based questionnaire which will be structured in the following sections:

• Demographics: Information on a variety of demographic variables will be collected in order to describe the characteristics of the study participants
• The Geriatric Depression Scale (GDS): To assess mood, the short version of the GDS will be used to detect the depressive symptoms in the elderly.
• Social Engagement Measure: The Berkman-Syme Social Network Index will be used to measure participants' social engagement and connections with families, friends, etc.
• The Mini-Mental State Examination (MMSE) Questionnaire: The MMSE will be used as a screening criterion to assess cognition.

1. Cognitive Assessments

• The Swinburne University Computerized Assessment Battery (SUCCAB) will be used as a primary measure to assess cognitive performance. Reliability and validity testing of this battery has demonstrated that the SUCCAB is sensitive to ageing, and has been shown to be particularly effective for measuring short-term changes in cognition for the elderly. The SUCCAB correlates strongly with memory subsets in the Wechsler Adult Intelligence Scales.

All participants who will be enrolled into the study will complete these assessments again at 3 months and at 6 months.

Interventions:

Fitting of hearing aids for Group A and Group B participants:

Participants will be fitted with two Blamey Saunders hearing aids known as the LOF for a period of 3 months. The hearing aids will be fitted according to the manufacturer's protocol, and explanation of the hearing aid usage, insertion of the aids and batteries along with a step-by-step guide on how to use the hearing aid will be given. A data logging function in the hearing aids will be used to assess hours of hearing aid use.

After 3 months (with wearing their hearing aids)

In addition, the Abbreviated Profile of Hearing Aid Benefit (APHAB), a self-assessment inventory, will be carried out with the assistance of the researcher to assess hearing aid benefit. Four scales of the APHAB will be assessed namely:

• Ease of communication (EC)
• Effects of background noise (BN)
• Effects of reverberation (RV), such as listening to sounds across a large room Aversiveness (AV), which will look at uncomfortable loudness of background sounds such as traffic and alarm bells.

Auditory training:

All participants enrolled into the study will undergo weekly auditory training for a period of 6 months. Over the 6 month period, each participant will undergo a two 12-week individualised speech tracking program, called the Continuous Discourse Speech Tracking, with and without hearing aids. Each test session will last for approximately 15 minutes. The procedure will be timed and scored in number of words per minute (wpm) transmitted. Tracking rate will be calculated as the number of words correctly repeated divided by the time elapsed.

Working Alliance Inventory:

At the end of the 6 month period after all examinations have been completed, Group A and B participants will complete a working alliance inventory, in order to evaluate the following: the quality of participant-researcher relationship, the collaborative nature of agreeing on tasks and goals of both auditory training and hearing aid compliance, and the outcome measures from auditory training provided to participants. Some randomized controlled trials have demonstrated that this evaluation is crucial for engaging, retaining and improving positive outcomes for study participants, and is vital for relationship-building.

Planned analysis

• Baseline comparison of the two groups in terms of demographics, cognition, mood, social engagement, hearing loss and hearing satisfaction using appropriate chi-square test, t-test and non-parametric Mann-Whitney tests.
• Comparison of the two groups in terms of changes in cognition, mood, social engagement from baseline to 3 months and 6 months, using a crossover analysis and multi-level models, allowing for any carry-over effect.
• The analysis of speech perception test results with and without hearing aids as a measure of the effectiveness of hearing aids and auditory training with and without hearing aids using multi-level models and again allowing for carry-over effects.
• The speech tracking rates from the two 12-week programs of speech tracking will be analysed for each participant using a learning model. This analysis will yield learning and forgetting rates with and without hearing aids. These learning and forgetting rates are valid measures of cognitive processes that are likely to be affected by the use of hearing and hearing aids. This data will also be analysed using multi-level models and again allowing for carry-over effects.

Contingency Plan: For participants who decide to discontinue auditory training because hearing aids have been beneficial, or decide to drop out entirely in the course of the auditory training program, they will be retained in the study as a third group, with a suitable modification to the analysis.