When Renita Adams puts a pot on the stove in her Virginia home, she also puts a rubber band around her wrist. The 62-year-old retiree prefers a tight band that squeezes a little bit, so she won’t forget it’s there–usually one of the colorful, stretchy rings that come wrapped around produce bundles. Her years as a nurse left her a perennial multitasker. Sometimes, when she goes to boil water or stick a meal in the oven, it just makes sense to get the laundry going, too, while she waits. But the rubber band is a critical step.
Adams has significant hearing loss. Even with her hearing aids in place, her doctors have told her that she only has about 10% acuity in her right ear (her left is better, but not great). If a kitchen timer were dinging, she likely wouldn’t notice. Then, there’s the ATV accident that left Adams with head trauma and took away her sense of smell about five years ago. If food is burning or metal is scorching, she can’t tell. Then, there’s the multiple sclerosis that sometimes makes her vision blurry and has left her with minimal sensation from the waist down. A phone vibrating in her pocket might be difficult to detect.
The rubber band is her own simple trick, devised after she’d ruined one too many stainless steel pots while trying to make tea or cook. The consistent pressure around her wrist helps her remember that the burner is on. With it, she can pivot between tasks and still know to check the stove after a few minutes. It’s one of many small ways that Adams has adapted to sensory loss, and one of the many ways that her disabilities have altered her day-to-day life.
Adams is not alone. Though the exact numbers aren’t certain, up to an estimated 15% of adults in the U.S. deal with dual sensory loss–defined as impaired vision and hearing–according to a 2020 epidemiology study. When you account for other sensory impairments like smell and taste loss, processing disorders, and reduced physical sensation, many more people are managing some version of multiple sensory loss. And prevalence increases with age. In a 2019 study of about 2,000 adults aged 70-79 years, 26% had two or more sensory impairments.
For those lucky enough to reach senior citizenship, some degree of diminished sensory capacity is essentially a given, explained Philip Hwang, an epidemiologist studying the association between dementia and sensory loss at the University of Washington. “Sensory loss is considered an age-related condition,” Hwang said. The conductive hairs inside our ears, our nasal nerves, and our eyes all degrade with wear and time. Not everyone will reach a clinical level of impairment, but almost all will experience declines.
The covid-19 pandemic has added onto those background levels of sensory loss and led to many more younger people grappling with impairments. It’s well known by now that the virus can decimate a person’s ability to taste and smell. Some recover, partially or fully; others haven’t yet. Emerging research further suggests that covid infection can cause certain types of hearing loss by damaging the nervous system. The past 3+ years have produced innumerable additional people newly maneuvering through the world with reduced sensory acuity. I am one of them.
A covid infection robbed me of most of my ability to smell and taste in November 2022. A couple of months later, I developed partial hearing loss on one side (apparently unrelated to my covid illness). The back-to-back blows of dulled senses catapulted me into a wholly different version of reality from what I’d previously inhabited. My world grew suddenly dimmer. It felt as if, over the course of just a few weeks, I went from a hyper-effective receiver– a perfectly calibrated satellite–to a dud piece of equipment. For the first time in my life, I began having to work consciously, not just to make sense of the world around me but to even amass baseline observations on it. I felt, and sometimes still feel, stuck in an inescapable sensory deprivation chamber. When people describe smells, tastes, or sounds that I can’t perceive, I beat against the ceiling of my own brain in frustration. I feel FOMO over exhaust fumes. There is so much that I’m missing, and I am still adjusting. Among the new things I am navigating: uncertainty and anxiety over what my multiple sensory struggles might mean for my future.
Beyond the challenges of daily life that can come with having impaired senses, research increasingly suggests that combined sensory losses may have compounding neurological, psychological, and physical consequences. A sensory deprivation tank for a few hours might be restorative, relaxing, or even boost cognition and focus. But when your brain is deprived of sensory input long-term, the outcome is very different.
Research has linked sensory loss with increased dementia risk, other cognitive impairments, depression, social isolation, reduced physical activity, and shifts in brain structure. The more severe and the more varied those impairments are, the stronger the associations. The direction of those links isn’t always clear (i.e., does sensory loss cause dementia or just serve as an early warning sign?), and big unanswered questions remain. Most research has focused on older adults, and so little is understood about the consequences of sensory loss before middle age. But it’s apparent that sensory feedback loops dictate a lot about both body and brain.
First, a small, necessary explanation: Sensory loss in adulthood or old age is different from being born with sensory impairments. The way that lifelong deaf people navigate and compensate for their inability to hear, for instance, is different from the way that older adults who progressively lose their hearing might. Neuroplasticity–your brain’s capacity to adapt to change–lessens with age. An infant is better equipped to adjust to hearing loss, anosmia, or blindness than a teenager, and a teenager better equipped than a 60 year old. Lifelong deaf or hard-of-hearing people do not have general cognitive impairments because of their deafness, emphasized Kate Slade, a neuropsychologist studying age-related hearing loss at Lancaster University in the UK.
Yet when hearing loss develops over time in adults, brain and cognitive changes do seem to accompany it, Slade explained. “We think of hearing as happening in the ear, but that’s not really the case,” Slade said. Sound enters through the ear, but “our brain provides the top-down information to help us put together the messages that we’re hearing. We might compare them to something we’ve heard in the past to fill in blanks if we miss something, or use other processes to help us understand sentences and full conversations.” The same is true across our senses. With sensory loss, the brain misses out on information and either has to work to fill in the gaps or simply can’t produce a coherent translation.
In those who develop impaired hearing in late life, the brain’s auditory cortex shrinks. The same phenomenon of regional brain atrophy has also been observed with sight and smell loss. These findings line up with the “use it or lose it” hypothesis, said Willa Brenowitz, an epidemiologist who studies the relationship between sensory loss and dementia at Kaiser Permanente’s Center for Health Research. Some studies have also indicated that other brain regions, like the hippocampus– critical for memory–may shrink along with hearing loss or other sensory changes, Brenowitz noted.
In yet other brain areas, certain studies have observed increased neural connections or boosted activity with sensory declines. Slade pointed to research that’s compared older adults with hearing loss to their counterparts without sensory impairment. When researchers gave each group an auditory task, EEG scans showed more electrical signals firing in parts of the brain responsible for complex cognition in the group with hearing loss than the control group.
The speech motor cortex, which is involved in mouth and tongue movement, also seems to functionally change with age-related hearing impairment, she added. Some studies have noted increased activity in the speech motor cortex in seniors, compared with those in midlife.
It could be easy to mistake the idea of increased brain connectivity and activity as a net good– perhaps it’s a sign of the nervous system adapting or developing some super-sensory alternative. But often, that doesn’t seem to be the case. Instead, a more active brain can simply indicate how hard someone’s nervous system has to work to make up for their sensory loss. And brains have limited resources. In another of Slade’s studies, she and her co-researchers monitored people as they tried to complete auditory tasks in increasingly challenging circumstances. The more background noise and muffled signals, the more people exhibited signs of physical exertion. Their heart rates went up, and their pupils dilated. Sensing the world takes measurable, quantifiable effort–which can become exhausting and limit a person’s ability to manage other tasks.
This increased cognitive burden is one working theory of why sensory loss and dementia are linked. As Hwang describes it, “those with sensory impairments have decreased ability to process information from the outside world, which causes greater cognitive load in their brains. And so it makes it much harder for them to perform other tasks related to cognition.” Over time, this stress might lead to overall declines and dementia.
Hearing loss in middle age, between ages 45 and 65, is one of the most significant risk factors for dementia. A 2020 Lancet report found that hearing loss in midlife approximately doubles dementia risk. In studies of older adults, multiple sensory loss has been shown to compound that increased risk.
“However you cut it or slice it, having worse sensory function in multiple domains is associated with a much higher risk of dementia,” said Brenowitz. She’s conducted multiple studies that examine how sensory impairment and cognitive loss intersect. In one 2019 analysis tracking hundreds of 70+ year-old participants through time, Brenowitz found 19% developed dementia: 12% of those with no sensory impairment, 19% of those with one, and 28% of those with multiple. Out of all the senses the study assessed–vision, hearing, touch, and olfaction–smell loss was the impairment most strongly linked with developing dementia.
In another 2020 follow-up study, Brenowitz and her co-researchers noted that those with severe multisensory loss were more than twice as likely to develop dementia over a 10-year period. And that even those with mid-level sensory loss were significantly more likely to end up with cognitive declines than those without any sensory impairments at all. “I don’t know exactly what that means for people experiencing changes due to covid or other viruses,” Brenowitz said.
Again, it’s unclear exactly what the relationship is between sensory loss and dementia. Maybe impaired senses lead to impaired brain function, or maybe impaired brain function hampers the senses. There might also be less-direct pathways at play.
Another theory, Hwang explains, is that people with sensory impairments often become socially isolated and less able to engage in healthy behaviors like exercise and spending quality time with friends and family. As a result, they become more at risk of dementia. Our world isn’t built for people with disabilities, and it can be difficult to navigate travel, entertainment, and public spaces without accommodations. Staying socially and physically active are thought to be two of the most protective behaviors against cognitive decline, said Hwang. By impeding people’s independence and freedom, sensory losses might indirectly lead to worse cognitive outcomes.
In Virginia, Adams has noticed some of this dynamic play out in her own life. Not all of her sensory difficulties are so easily solved with rubber band workarounds. In our phone conversation, she described skipping church functions she used to love attending because they are so loud that it overwhelms her. For the same reason, she doesn’t go out to eat much anymore, and only to very specific, quiet, places. And, though she cherishes time spent with her loved ones, sometimes conversations can stress her out–particularly when reminders of her other sensory struggles come up. When she’s with friends or family “and they start talking about smelling something, it’s kind of like my heart drops to my feet,” she said. Her husband, she noted, no longer references smells, because he knows it “triggers that heart-drop feeling.”
She still enjoys regular walks in the mountains that surround her home. On the day we spoke, she’d already gone on one morning hike with her husband and pet doberman, Gracie, and had plans for another later in the day. But she has held off on getting the cochlear implant surgery her doctors say would drastically improve her hearing, out of worry about the side effects. Cochlear implants can impair balance and cause vertigo. “My greatest fear is the unbalance,” Adams said. If she were less steady on her feet, hiking might become impossible.
Depression and anxiety, too, are associated with sensory loss and become more common with multiple sensory loss, according to numerous studies. Independent of sensory impairment, depression is also associated with cognitive declines in later life, on its own. The mental health effects of sensory loss are yet another potential way such declines might harm cognition.
Although Adams tries to avoid focusing on the negative, “it’s getting more difficult to keep positive,” she told me. Her type of hearing loss is progressive. So is her multiple sclerosis. Both will likely continue to get worse. And, despite scent-training efforts, she hasn’t noticed a marked improvement in her ability to smell, either. Her possible future, where communication with loved ones becomes even more difficult and where her ability to experience the world narrows, weighs on her.
She regularly considers trying to take up sign language, but she would prefer an in-person class, and those are scant in her area. She also worries she’s too old to learn an entirely new language. On occasion, groups at her church do put on musical performances with sign interpreters. She can’t understand what they are saying, but she still watches the interpreters with enthusiasm and interest. “To me, it’s very amazing and spiritual, I guess you’d say. It’s very cool how they do each song in sign.”
Adams remains apprehensive about cochlear implants, and her hearing aids can’t fully compensate for her profound hearing loss, yet corrective treatments can make a difference for many. Hearing aids can reduce dementia risk by 42% in people with hearing loss, according to one study published in April. To reach that finding, the researchers analyzed 12 years of data on 437,704 people. In the case of vision loss, cataract surgery and other eye interventions are thought to yield similar results. In a 2021 study, researchers found that cataract removal reduced dementia risk by nearly 30%.
Yet these stats are muddled by questions of confounding factors and access, noted Hwang and Brenowitz. In the U.S., hearing aids aren’t generally covered under insurance. Medicare does not cover any portion of the cost for hearing aid fittings or devices. They cost thousands of dollars. Surgeries, too, can quickly become expensive, even with insurance. Plus, simply getting back and forth to doctor appointments can be difficult for many seniors who may not be able to drive, have access to a car, or be able to afford assistance. It’s possible that hearing aids and cataract surgery are associated with decreased dementia risk, in part, because the people who can get corrective devices and surgeries simply have more resources and support. Maybe it’s not getting the hearing aid that makes the biggest difference, but the circumstances that allow for someone to get a hearing aid versus the circumstances that don’t.
Regardless, Slade, Hwang, and Brenowitz all stressed the importance of going to the doctor for regular check-ups, including ear and eye exams, when possible. Keeping tabs on sensory acuity, catching any changes early, and getting fitted for proper correctives can make a huge difference in quality of life. With tools like glasses and hearing aids, and minor surgery, people with sensory impairments can more easily remain active and socially engaged. Currently, no guaranteed corrective for smell loss exists. Scent training may help some, but not all. However, researchers and non-profit groups like the U.K.-based AbScent, which Adams has connected with, are working to find better treatments.
Every expert I spoke with emphasized that sensory losses don’t automatically sentence someone to isolation or dementia. There are always things that people can do to improve and maintain their health. Very few reach old age without some sort of sensory decline, but life can still be full of experiences worth having.
I find myself reaching out to touch things much more often: a leaf on a tree or my partner’s arm. Adams described a similar impulse. Though she can’t smell her rose bushes in the spring anymore, she frequently finds herself rubbing the flowers’ petals between her fingers, noting the soft, satiny feeling. She’s also learned to crochet. She taught herself using YouTube videos during the pandemic lockdown, and now regularly crochets with her friends. “You don’t have to be able to hear or smell to crochet,” she said. Instead, she can focus on her hands, and the information they provide.
I asked her if she’d noticed that anything about her thinking had changed with her sensory impairments. I expected she might say that her thoughts come slower, or that it’s harder to feel present, or that she just gets more tired more quickly being out in the world–things that I’ve felt. Instead, she surprised me.
“I definitely have more empathy than I used to have,” Adams said. She added that she feels, now, between retirement and her health changes, she has more time and space to “think and digest things.” She approaches problems and people differently than she might once have. She’s become involved in community organizing over the past few years. She wants to see her town get a homeless shelter, and she hopes for more local support for people and families grappling with drug addiction, which she says is an epidemic in her area. It would be easy for Adams to retreat from the world, full of sounds and smells she can no longer detect. Instead, she’s finding different ways to be a part of it.
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