Dementia can affect much more than the ability to remember. Depending on the type of dementia and the areas of the brain affected, a person may also have changes in how they interpret what they see, hear, touch, smell, or taste.

This is important because sensory changes can affect how a person understands and responds to the world around them.

There is also an important distinction between having a problem with a sense itself and having difficulty processing sensory information in the brain.

Vision: Seeing Is Not Always the Same as Understanding

Dementia can affect visual processing in several ways. A person may have difficulty judging distance, recognizing objects or faces, navigating spaces, or interpreting what they see. 

This can sometimes look like a memory problem. For example, a person may look directly at a familiar object but not understand what it is used for. They may also have difficulty finding something that is directly in front of them.

Certain types of dementia can cause particularly significant visual or spatial changes. In Lewy body dementia, for example, visual hallucinations can occur. In posterior cortical atrophy, changes in visual processing can be a prominent early feature.

Posterior cortical atrophy is a condition where brain cells in the back part of the brain slowly die. Because the damage occurs in the brain’s visual-processing region, the person’s ability to understand visual and spatial information gradually changes.

People often have trouble reading, judging distances, or reaching for objects. They may struggle to recognize familiar faces or everyday items, and some experience difficulty with math or calculations.

It is also important to remember that ordinary vision problems, such as cataracts, glaucoma, or changes in visual acuity, can occur at the same time as dementia and should not automatically be attributed to dementia.

Hearing: Hearing the Sound Is Not the Same as Understanding It

Hearing loss is common in older adults, but dementia can also affect how the brain processes and understands auditory information.

A person may hear someone speaking but have difficulty following a conversation, particularly when several people are talking, or there is background noise. This can be especially challenging in busy dining rooms, restaurants, television-filled rooms, or group activities. 

This is why environments with competing sounds or multiple speakers can feel confusing or exhausting for someone with dementia. The brain is working harder to interpret visual and spatial cues that are no longer processed efficiently.  It is important, therefore, to reduce sensory overload whenever possible and offer clear, calm communication.

Hearing loss and dementia can also compound one another. When hearing is impaired, the brain has less clear information to work with. A person may appear confused or withdrawn when the underlying problem is that they simply cannot hear or process what is being said clearly.

Checking hearing is therefore an important part of understanding changes in communication.

Touch: More Than Feeling a Hand or an Object

Touch provides information about temperature, pressure, texture, pain, and physical contact. Dementia can alter how sensory information is interpreted or responded to.

Some people may become more sensitive to touch, while others may appear less responsive. A person who becomes distressed during bathing or dressing may not simply be “resisting care.” Water temperature, clothing texture, pressure from a caregiver’s hands, or unexpected physical contact may be uncomfortable or difficult to interpret.

Pain can also be difficult to recognize and communicate, particularly when a person’s ability to describe what they are experiencing has changed.

Smell and Taste: Changes That Can Affect More Than Mealtimes

Changes in smell and taste can occur in dementia and can affect appetite, food preferences and enjoyment of meals.

A person may find familiar foods different or less appealing. Changes in smell can also affect how food is experienced because smell contributes significantly to flavour.

However, changes in smell or taste can have many causes, including medications, illness, aging and other neurological conditions. They should not automatically be assumed to be caused by dementia.

When the Senses Affect Everyday Behaviour

Changes in sensory processing can show up in everyday actions that may seem unrelated to the senses. A person may not be able to explain what feels wrong, but their actions can provide clues.

Consider some common examples:

The behaviour: A person wears a heavy sweater or several layers of clothing on a warm day.

What might be happening: They may have difficulty judging temperature, may not recognize that they are too warm, or may no longer be able to communicate discomfort clearly. Clothing may also have become part of a familiar routine.

What may help: Check the person’s body temperature and comfort rather than assuming they are choosing inappropriate clothing. Offer lighter layers and simple choices, and look for other signs that they are too warm or cold. Changes in temperature sensitivity can have other medical causes, so persistent or unusual changes should be assessed.

The behaviour: A person becomes frightened by something in a corner of the room or insists that there is an animal, person, or object that is not actually there.

What might be happening: Changes in visual processing can cause a shadow, reflection, pattern, or object to be misinterpreted. Hallucinations can also occur in some forms of dementia, particularly dementia with Lewy bodies.

What may help: Check the lighting and surroundings. Reduce shadows and reflections, remove confusing visual patterns where possible, and move the person to a better-lit area. 

If the person is seeing something that is not there, arguing about what they see is unlikely to help. Instead, acknowledge that the experience is real to them and provide reassurance. 

New or sudden hallucinations should be medically assessed because infections, dehydration, medications, vision problems, and other conditions can also cause them. The person could be experiencing delirium. 

The behaviour: A person repeatedly pulls at a shirt, refuses a particular item of clothing, or becomes distressed during dressing.

What might be happening: The clothing may feel uncomfortable, scratchy, tight, or unfamiliar. An itchy label, strong detergent smell, or unfamiliar fabric can also cause discomfort. The person may no longer be able to explain what is bothering them.

What may help: Check the fit, fabric, seams, and labels. Consider whether a different detergent or familiar clothing would help. Offer a small number of choices rather than presenting a full wardrobe of options.

The behaviour: A person refuses to take a bath or attempts to step into a bathtub but misjudges the height or depth, or appears unsure about where to place their feet.

What might be happening: The person may be having difficulty with visuospatial processing — the brain’s ability to understand where objects are in relation to the body and to judge distance, depth, height and position. 

The bathtub may be completely visible, but the person may not accurately interpret how high the edge is or how far down they need to step. 

Similar difficulties can affect walking through doorways, navigating stairs, finding a chair, or moving around unfamiliar spaces. Changes in visuospatial abilities can occur in several types of dementia and may contribute to falls.

What may help: Improve lighting, reduce visual clutter, and use clear colour contrast to make important surfaces and edges easier to distinguish.  For example, a contrasting, non-slip bath mat that clearly defines the tub floor and provides a stable surface for footing.

Provide stable support when transferring. Consider whether the bathing setup can be made safer. For example, using an appropriate shower arrangement rather than requiring the person to step over a high bathtub wall. An occupational or physical therapist can assess the person’s mobility, environment and equipment needs.

It is important to note, however, that not every change in behaviour has a sensory explanation. Pain, illness, medication effects, constipation, infection, fatigue, communication difficulties and many other factors can also affect how a person responds.

Instead, sensory processing should be one part of the assessment. Ask:

What might the person be seeing, hearing, feeling, smelling, or tasting right now?

Could something in the environment be difficult to process?

Could a sensory impairment be making the situation harder?

What simple change could make the information easier to understand or the environment more comfortable?

Understanding Changes How We Care

Dementia can change more than memory. It can change how a person sees, hears, feels, interprets, and responds to the world around them. When we understand these changes, everyday actions can begin to make more sense.

Education gives us another way to look at what we see. 

Knowledge also gives professionals greater confidence in their work. When we understand what may be happening and have practical strategies to respond, we are less likely to feel that we are simply reacting to one difficult situation after another. We can make more informed decisions, recognize when something requires further assessment, and feel more capable of providing care that makes a difference.

Just as importantly, understanding the reason behind what we do can reconnect us with the meaning in our work. That awareness can bring purpose to the everyday work of care and remind us that what we do matters.

For families and professionals alike, education is a form of protection. The more we understand about dementia, the better prepared we are to recognize changes, reduce avoidable risks, and support the person as an individual.

We will not always know exactly what a person is experiencing, but we can keep learning, keep observing, and keep asking better questions.

Understanding dementia doesn’t just give us more knowledge. It gives us more ways to help. 

At Dementia Solutions, we’ve made it our mission to demystify dementia behaviour and continue to explore person-centred, creative, non-pharmacological solutions to manage dementia-related behaviours. We believe that awareness creation and skill-building through education is the most effective and powerful tool we have to promote and maintain the well-being of both the person with dementia and their caregiver.