Hearing aids for adults: what the evidence shows about outcomes — and the risks of leaving hearing loss untreated

If you or someone you care for has hearing loss, you might be wondering about the real benefits of hearing aids. You might also have questions about what happens if hearing loss goes unaddressed. Research studies help us understand the potential impacts of hearing aids and the broader effects of hearing loss.

This article looks at what some key studies have found. We will cover how hearing aids can improve daily life and what research suggests about the link between untreated hearing loss and other health factors, like cognitive decline.

How Hearing Aids Can Improve Daily Life

One important review of research, published by Cochrane in 2017, looked at the effects of hearing aids for adults with mild to moderate hearing loss [1]. Cochrane reviews are known for carefully examining many studies to draw conclusions.

The purpose of this review was to evaluate how hearing aids affect adults with mild to moderate hearing loss. The researchers wanted to see if hearing aids help reduce the negative impacts of hearing loss and improve participation in everyday life [1].

What the Cochrane Review Looked At

The review included five randomized controlled trials (RCTs) with a total of 825 participants. These studies were conducted in the USA and Europe and published between 1987 and 2017. Participants in these studies had mild to moderate hearing loss, and their average age ranged from 69 to 83 years. The studies lasted between six weeks and six months [1].

The main outcomes the review focused on were: * Hearing-specific health-related quality of life: This measures how much hearing loss affects a person's daily activities and well-being related to their hearing. * General health-related quality of life: This looks at overall well-being. * Listening ability: This assesses how well a person can understand sounds and speech [1].

Key Findings on Hearing Aids

The Cochrane review found several beneficial effects of hearing aids [1]:

• Hearing-Specific Quality of Life: There was a large beneficial effect of hearing aids on hearing-specific health-related quality of life. This was measured using a tool called the Hearing Handicap Inventory for the Elderly (HHIE), which has a scale from 1 to 100. Compared to not using hearing aids or using a placebo, hearing aid users showed a mean difference of -26.47 points (95% confidence interval -42.16 to -10.77). This evidence was considered moderate-quality [1]. This suggests that hearing aids significantly improve how people feel about their hearing in daily life.

• General Quality of Life: The review also found a small beneficial effect of hearing aids on general health-related quality of life. This evidence was also considered moderate-quality [1].

• Listening Ability: Hearing aids showed a large beneficial effect on listening ability. This evidence was rated as moderate-quality [1]. This means people could understand sounds and speech much better with hearing aids.

• Adverse Effects: Only one study in the review, involving 48 participants, measured adverse effects. No adverse effects were reported in that study. However, the quality of this evidence was rated as very low [1].

What These Findings Mean

The available evidence from this Cochrane review suggests that hearing aids are effective. They can improve hearing-specific health-related quality of life, general health-related quality of life, and listening ability for adults with mild to moderate hearing loss [1].

The review concluded that this evidence supports the widespread use of hearing aids as a first step for managing hearing difficulties in those who seek help [1].

Untreated Hearing Loss and Broader Health

Beyond the direct impact on hearing and quality of life, researchers have also explored the potential links between untreated hearing loss and other health conditions. One area of focus has been cognitive decline, including dementia.

Hearing Loss as a Modifiable Risk Factor

The 2020 report of the Lancet Commission on dementia prevention, intervention, and care listed hearing loss among several modifiable risk factors for dementia [2]. This means that hearing loss is a factor that might be changed or addressed, and it is associated with an increased risk of dementia. This report highlights the importance of addressing hearing loss as part of a broader strategy for brain health [2].

It is important to understand that listing hearing loss as a modifiable risk factor means there is an association or link. It does not mean that hearing loss causes dementia, nor does it mean that treating hearing loss prevents dementia. Instead, it suggests that addressing hearing loss could be one part of a larger approach to reducing dementia risk.

The ACHIEVE Trial: Hearing Aids and Cognitive Decline

Given the observed association between hearing loss and cognitive decline, a major study called the ACHIEVE trial aimed to investigate whether using hearing aids could reduce cognitive decline in older adults with hearing loss [3]. This study, published in The Lancet in 2023, is significant because it was a large, randomized controlled trial specifically designed to answer this question.

How the ACHIEVE Trial Was Designed

The ACHIEVE study was a multicentre, randomized controlled trial conducted across four community study sites in the USA. It involved adults aged 70–84 years who had untreated hearing loss and no major cognitive impairment [3].

Participants were divided into two groups: 1. Hearing Intervention Group: Received audiological counselling and hearing aids. 2. Health Education Control Group: Received individual sessions with a health educator covering topics on chronic disease prevention [3].

The study followed participants for three years. The main goal was to measure changes in a global cognition score over this period [3].

Participants in the Study

The study screened over 3,000 participants and randomly assigned 977 people to either the hearing intervention (490 people) or the health education control (487 people). The average age of the participants was 76.8 years. About 54% were female, and 46% were male. Most participants (88%) were White [3].

The participants came from two different groups: * ARIC study participants: These individuals were already part of a long-standing observational study on cardiovascular health. They tended to be older, had more risk factors for cognitive decline, and had lower baseline cognitive scores. * De novo community volunteers: These were healthy volunteers recruited specifically for the ACHIEVE trial. They generally had fewer risk factors for cognitive decline and higher baseline cognitive scores [3].

This distinction between the two groups of participants became important in the study's findings.

Overall Results: No Significant Difference in Cognitive Decline

In the main analysis, which combined both the ARIC and de novo cohorts, the ACHIEVE trial found no significant difference in three-year cognitive change between the hearing intervention group and the health education control group [3].

Specifically, the three-year cognitive change (measured in standard deviation units) was -0.200 in the hearing intervention group and -0.202 in the control group. The difference between these two groups was 0.002, which was not statistically significant (p=0.96) [3].

This means that, for the overall group of older adults with hearing loss in this study, the hearing intervention (hearing aids and counselling) did not reduce cognitive decline over three years compared to the health education control [3].

A Closer Look: Findings in the At-Risk Subgroup

While the overall result showed no benefit, the researchers conducted a prespecified sensitivity analysis. This analysis looked at whether the effect of the hearing intervention differed between the two types of participant groups (ARIC vs. de novo) [3].

This sensitivity analysis revealed a significant difference in the effect of the hearing intervention on three-year cognitive change between the ARIC and de novo cohorts (p-interaction=0.010) [3].

What does this mean? The findings suggest that a hearing intervention might reduce cognitive change over three years in populations of older adults who are at increased risk for cognitive decline. However, it might not have the same effect in populations at decreased risk for cognitive decline [3].

The ARIC participants, who were older and had more risk factors for cognitive decline, showed a potential benefit from the hearing intervention that was not seen in the healthier de novo volunteers [3].

What These Findings Mean

The ACHIEVE trial provides important insights: * Overall Population: For a broad group of cognitively healthy older adults with hearing loss, a hearing intervention (hearing aids and audiological counselling) did not reduce cognitive decline over three years compared to health education [3]. * At-Risk Subgroup: However, in a subgroup of older adults who had more risk factors for cognitive decline, the hearing intervention showed a potential to reduce cognitive change [3].

It's crucial to interpret these findings carefully. The study did not find a general cognitive benefit from hearing aids across all participants. However, it opens the door for further research into specific populations who might benefit more from hearing interventions in terms of cognitive health.

No significant adverse events attributed to the study were reported in either the hearing intervention or health education control groups [3].

Limitations of Research Studies

It is important to remember that all research studies have limitations.

For the Cochrane review on hearing aids [1]: * The studies included varied in their risk of bias. Many had a high risk for performance and detection bias because participants and researchers were often aware of who was receiving hearing aids, which could influence results. * Adverse effects were measured in only one study, meaning there is limited information on potential negative impacts. * The review suggested a need for more consistency in how benefits are measured and for more placebo-controlled studies to increase confidence in the findings.

For the ACHIEVE trial on cognitive decline [3]: * The study followed participants for three years. Longer-term studies might show different results. * The participants were primarily White, which means the findings might not apply equally to other ethnic groups. * The "at-risk" subgroup finding was from a sensitivity analysis, not the primary outcome for the entire group. This means it suggests a potential effect that needs further confirmation in dedicated studies. * The control group received health education, which itself could have some positive impact on health, potentially making it harder to see a difference from the hearing intervention.

These limitations do not invalidate the findings but help us understand the scope and certainty of the conclusions.

The Bottom Line

Research indicates that hearing aids can significantly improve hearing-specific quality of life, general quality of life, and listening ability for adults with mild to moderate hearing loss [1]. This suggests a clear benefit for daily communication and well-being.

Furthermore, hearing loss has been identified as a modifiable risk factor for dementia [2]. This highlights the importance of addressing hearing loss as part of a comprehensive approach to health, even if the direct impact of hearing aids on preventing cognitive decline is still being understood.

The ACHIEVE trial, a major study on hearing aids and cognitive decline, did not find an overall reduction in cognitive decline for all older adults with hearing loss over three years [3]. However, it did suggest a potential benefit for those who are at increased risk for cognitive decline [3]. This means that while hearing aids are not a "cure" for cognitive decline, they might play a role for certain individuals.

If you are experiencing hearing loss, understanding your options is important. An audiologist can assess your hearing, discuss your specific needs, and help you understand whether a hearing intervention, such as hearing aids, is suitable for you. You can find out more about audiology services in your area by looking at resources such as those focused on Calgary or Edmonton.

Ultimately, decisions about hearing health should be made with the guidance of a licensed professional who can provide personalized advice based on your individual health profile and circumstances.