BLOG: Vision, hearing loss linked to cognitive loss
There is a strong connection between sensory input and cognition. In fact, according to Livingston and colleagues, hearing loss is the leading modifiable risk factor for dementia.
The prevalence of hearing loss doubles with every decade of life, affecting about two-thirds of those over age 70, and yet it is vastly under-corrected, with less than 25% of those affected using hearing aids (Lin et al.)
Functional MRI studies have shown that with even a mild amount of hearing loss, the brain begins to compensate for the lost sensory input. The visual system helps fill in the blanks via lip reading and other visual cues.
While this may be helpful in the moment, it shifts responsibility for hearing from the temporal lobes to the frontal lobe of the brain, increasing the cognitive load on the frontal lobe and reducing its cognitive reserves. In essence, the brain sacrifices executive function and memory tasks that are supposed to be handled by that part of the brain to try to regain needed sensory stimulation.
Now, imagine the impact on cognition if the individual also has vision problems on top of hearing impairment. We call this “dual sensory loss,” and it is typically associated with significant communication difficulties, a higher risk of falls, greater social isolation and depression (which also contribute to dementia), and more difficulty generally with activities of daily living.
The good news is that both vision and hearing loss can in many cases be corrected. There is evidence that we can begin to reverse the brain’s neural reorganization in as little as 6 months with properly fit hearing devices (Glick et al.), although it is not yet known whether the cognitive changes associated with long-term sensory loss can truly be reversed.
Because of the strong connection between hearing loss and cognition, I began assessing cognitive performance in my practice using a 5-minute, self-administered computerized screening tool called Cognivue Thrive. This validated, objective test evaluates memory, executive function, visual-spatial abilities, reaction time and processing speed.
When I see that cognitive performance is lower than expected, I first address the patient’s hearing loss. I find that about 77% will have better cognitive test performance 60 days after being fit with hearing aids. Because patients may have multiple risk factors for dementia, I also ask them about their vision and other potentially untreated conditions, such as diabetes, hypertension and sleep disorders. If their cognitive performance doesn’t improve, a full workup by their primary care physician or a neurologist may be in order.
There are great opportunities for audiologists and optometrists to work together to modify our patients’ risks for dementia and falls. Here are 5 things you can do this year:
- Encourage everyone over 40 to have a hearing test;
- Ask your patients if they are having any difficulty hearing in situations where there is background noise. If yes (or if they struggle to hear a mask-wearing speaker) they probably need a hearing test;
- Establish referral relationships with audiologists in your community;
- Consider hosting a hearing loss awareness month. Every January is vision loss awareness month in my practice, when I try to pay extra attention to visual needs and make even more vision care referrals than usual; and
- If you don’t perform cognitive testing in your office, consider referring to someone who does.
I find that when patients understand the link between cognition and their senses, they are more motivated to address hearing or vision loss. The potential to protect their brain helps overcome the barriers of cost, technological change and social stigma.
References:
Cahn-Hidalgo D, et al. World J Psychiatr. 2020;doi:10.5498/wjp.v10.i1.1.
Glick H, Sharma A. The brain on hearing aids: Can treatment with hearing aids improve neurocognitive function in age-related hearing loss? Hearing Rev. 2021. https://www.hearingreview.com/hearing-products/hearing-aids/neurocognitive-function.
Lin FR, et al. Aging Ment Health. 2014;doi:10.1080/13607863.2014.915924.
Livingston G, et al. Lancet. 2020;doi.org/10.1016/S0140-6736(20)30367-6.
For more information:
Jill Davis, AuD, has a doctorate of audiology and a bachelor’s degree in communication sciences and disorders from the University of Cincinnati. She is the owner of Victory Hearing & Balance in Austin, Texas, where she specializes in hearing loss, auditory processing disorders, hearing protection, auditory training, cochlear implants and advanced digital hearing aid fittings. She is passionate about improving communication for her patients.
Disclaimer: The views and opinions expressed in this blog are those of the authors and do not necessarily reflect the official policy or position of the Neuro-Optometric Rehabilitation Association unless otherwise noted. This blog is for informational purposes only and is not a substitute for the professional medical advice of a physician. NORA does not recommend or endorse any specific tests, physicians, products or procedures. For more on our website and online content, click here.
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