Your loved one won’t step over a dark rug, because to them it looks like a hole in the floor. Or they tell you to stop yelling at them, when you’re speaking in a perfectly normal voice.
Careblazer, when we talk about dementia we usually focus on memory and behavior. But dementia also affects all of the senses: what we’re able to see, hear, taste, touch and smell. Those changes can make daily life feel scary or very confusing, for the person with dementia and for you.
Here’s how dementia changes the five senses, and how to tell normal aging from a symptom of dementia.
Vision Changes in Dementia
Normal Aging vs Dementia-Related Vision Changes
As we age, it’s common to need reading glasses, or brighter light to see clearly. That’s totally normal. In normal aging we might also notice slower focusing, small changes in color vision, some light sensitivity, more trouble driving at night, or the need for a new prescription. But we still understand what we’re seeing.
In dementia, the eyes could technically be fine. What changes is how the brain interprets what it sees. Everything we see with our eyes is filtered through the brain, and in dementia that interpretation is disrupted. It’s not just aging eyes. It’s literally struggling to make sense of what they’re seeing.
How Vision Can Change in Dementia
People with dementia often have trouble with spatial awareness, or even depth perception. They might misjudge how far away a chair is, try to sit down, and miss it. They might misread a dark rug on the floor as a hole.
Another common change is trouble recognizing faces or objects. We hear a lot about people with dementia forgetting who somebody is. What isn’t talked about much is prosopagnosia, which is basically facial blindness. They don’t recognize the face they’re looking at.
Imagine seeing one of your loved ones and not being able to recognize their face.
The same can happen with objects. They might look at a fork and not recognize that it’s a fork, so they look confused about what they’re supposed to do with it. That’s visual misrecognition: the brain struggling to process what the eyes take in.
Which Types of Dementia Affect Vision
Changes in vision and visual processing are often seen in Lewy body dementia and Parkinson’s disease dementia, where visual hallucinations are common. A visual hallucination is when the person sees something that isn’t there at all. Their brain is showing them that it’s there.
We also see it in posterior cortical atrophy, where vision and facial awareness are disrupted. And in Alzheimer’s disease, visual confusion and trouble recognizing people, places and things often start to appear in the middle to late stages.
Signs You Might See
- Walking very cautiously, especially over a rug or a change in the flooring
- Treating a shiny floor as if it’s wet
- Saying something like, “Don’t make me step over that hole”
- Walking around something that, to you, isn’t there
- Talking about something they’re seeing that isn’t there
- Swatting or taking off things that aren’t there, like brushing bugs off themselves or moving people away
- Staring blankly at you or someone else, as if they don’t recognize them at all
These are all clues that their visual processing may be changing. I go deeper into each of these, and how to keep your loved one safe, in how dementia changes vision.
Hearing Changes in Dementia
Normal Aging vs Dementia-Related Hearing Problems
Many older adults have some hearing loss. That’s normal aging. Dementia goes a step further.
People with dementia might hear sounds normally, but have trouble processing what they’re hearing. They hear you talking, but they don’t understand the words you’re saying. Or they can’t stay focused on what they’re hearing when there are other noises around.
At a restaurant, for example, they might have an extremely hard time hearing you because of all the other noise.
In dementia, the ears can work just fine. It’s the brain’s ability to interpret what they hear, and to filter out background noise, that’s often damaged.
Which Types of Dementia Affect Hearing
We see this in frontotemporal dementia, especially the language variants, where understanding words is difficult even with normal hearing. In Alzheimer’s disease, people often have trouble understanding and following conversation, especially in the later stages. And in vascular dementia, depending on where the damage is in the brain, comprehension can be affected.
What You Might Notice
- Saying “stop yelling at me” when you’re speaking in a normal tone, because your words sound distorted or harsher than you mean them
- Nodding along politely without really engaging, then being confused later, because they wanted it to look like they understood
- Turning the TV up very loud even though their hearing is fine
- Saying “What?” over and over, because they can hear you but aren’t understanding you
What Helps
If you suspect this is happening, try facing your loved one when you speak to them. Reduce background noise. Speak slowly, and use short, direct phrases.
Touch and Physical Sensation in Dementia
How Normal Aging Differs From Dementia
As we age, we might become more sensitive to temperature and to pain. In dementia, the brain’s ability to sense touch and sensation can become unpredictable.
Some people seem unaware of pain. Others become overly sensitive, even to a light touch. Even the feel of water on their body can be painful to them. This can be seen in different types of dementia, including frontotemporal dementia, vascular dementia and Lewy body dementia.
Signs You Might See
- Becoming more sensitive to certain clothing: “Get this shirt off me, it’s itchy”
- Pulling away from hugs or touch in a way they never did before, because it feels painful or even threatening
- Holding a hot cup of tea without realizing it’s burning their hand
- Picking at their skin until it bleeds and scabs, because they’re trying to feel some sort of stimulation
With touch, dementia can go either way. They may need more stimulation, or the slightest bit can feel like too much.
Changes in Taste and Appetite
Normal Aging vs Taste Changes in Dementia
Taste naturally fades as we get older. But in dementia there’s often a strong or sudden desire for extra sugar in everything. Many people with dementia have a reduced ability to taste, and they develop a stronger preference for sweeter foods.
Signs You Might See
- Pouring sugar on pasta, or on cereal several times over
- Saying “You didn’t make this right” or “It tastes funny”
- Refusing vegetables or protein, but really wanting dessert
- Eating spoiled food, because they can’t tell it’s gone bad
A hint of sweetness in a meal, without making it totally sweet, can help encourage a more well-rounded, nutritious meal.
Changes in Smell and Safety Risks
Why Smell Loss Matters in Dementia
Smell is one of the earliest senses affected in Alzheimer’s disease. That’s why, when people are being tested for Alzheimer’s, they might be asked questions about smell or even given a smell test. I cover more on this in is smell loss an early warning sign of dementia.
In normal aging, our sense of smell might weaken over time, but we can still pick up strong odors. In dementia, the brain’s smell processing areas start to get damaged, and even strong odors can go totally unnoticed. This is most common in Alzheimer’s disease, but it can be seen in Lewy body dementia as well.
Smell loss is a big safety risk. Your loved one might not smell smoke. They might not smell a gas leak. They might not be able to tell that food has spoiled.
Signs You Might Notice
- Eating spoiled food without noticing it’s gone bad
- Not noticing the smell of smoke or gas
- Using too much perfume or cologne, because they can’t smell it
- Saying they don’t smell anything when other people comment on an odor
What Helps
If this is happening for your loved one, make sure there are working smoke detectors and gas detectors in the home, and keep checking for spoiled food. Ramp up the safety as much as you can to make up for the smell loss.
How Dementia Changes the Senses, Brought Together
Normal aging brings mild, gradual changes to our senses. Dementia changes how the brain understands and interprets what the senses take in. It can turn everyday sights, sounds and sensations into something frightening or confusing.
So when your loved one hesitates, misreads something, or reacts in a way that doesn’t make sense, it might not be memory loss or stubbornness. It might literally be the way their brain is interpreting the world right now.
Knowing that can help you keep a little compassion in those moments.
When you can’t tell whether a new reaction is the senses, the disease or something else, it helps to have people to ask. Inside the Care Collective, Careblazers meet with each other, with me and with other experts every week, so you can get answers to confusing questions and symptoms, and support from people who truly get it. You can learn more here.
