The Five Senses

The following is a chapter in our newest book, to come out this fall. More about it in later blogs.

senses: Sight, smell, hearing, taste, and touch; faculties by which the brain receives external stimuli.

The senses are the brain's information gathering system. When they are damaged, the information they deliver may be distorted from the beginning. Dementia itself doesn't damage the senses. Age can, or other illnesses can, but dementia doesn't.

However, attention deficit is a common dementia symptom. It limits one's ability to narrow their focus and pay selective attention. Everything is giving equal billing, making it difficult to choose what to ignore what to zero in on. This broader view sends fuzzier, less accurate information to the brain for processing, even when the senses themselves are not damaged. (reference)

In communication, when words and non-verbal cues picked up via these senses differ, it is human behavior to believe the cues over words. That's because words are symbols that must be decoded, requiring an extra processing step. Non-verbal cues are not so difficult to decode and therefore are processed more quickly.

It is important for a care partner to know not only what dementia has taken away, but also what is left to work with. For example, as language skills wane, a PlwD will turn to using non-verbal cues to communicate their own needs and wishes instead of words.

Vision. As a person ages, one's peripheral vision tends to narrow. Dementia tends to cause this to happen sooner. Thus a PlwD will probably have poor peripheral vision and as the dementia progresses their field of vision narrows to a small area right in front of them. They need you to stand inside their field of vision, but off to one side a little so that you don't block their whole field.

The quality of vision still left also degenerates with age, other health issues, and possibly even with dementia. Things that were once clear can become blurry, faded and distorted. Use bright color and contrasts to help with this. (Reference)

Hearing. Dementia does not make people hard of hearing and using a loud voice will not improve their ability to hear. The louder a voice, the more distorted the sound and the less it will be understood. However, many people with dementia are of the age where being hard of hearing is common. The higher registers tend to be more affected more than the low ones. Use a normal voice, pitched as low as possible, to have the best chance to be understood.

Unless some other problem has caused hearing damage, a person with dementia will usually be able to hear no matter how far they are into their journey--and may be able to comprehend as well. Use care with what you say around a PlwD who appears to be comatose or inattentive. Inappropriate words can cause great agitation.

Smell. There is some early research suggesting that Parkinson's disease (PD) starts in the nose, not the midbrain. An early PD symptom is loss of smell, which supports this idea. (Reference) LBD care partners often name loss of smell as an early symptom even when PD wasn't involved. The good news is odor receptors (olfactory nerves) reside in many areas of the body besides the nose, including the skin. This means that smell-based alternative therapies may still be helpful. (Reference)

Touch. Touch seems to be a long-lasting sense like hearing. This is especially true for the more sensitive areas of the body: lips and tongue, fingers and palms, soles of feet and genitalia. That's why you will see a PlwD touching things or putting them in their mouth. A person can also continue to feel and enjoy touching from others. Use a gentle but firm hand. Avoid a light feathery touch that might cause unpleasant feelings of tickling or even "bugs."

Taste. PlwD often have altered food preferences. Dementia may take away the ability to identify and remember tastes. But typical aging is even more of a problem. Like vision, the efficiency of the taste buds fades with age. Thus a person will tend to prefer sweets or other foods with strong tastes. The ability to enjoy food and the cultural processes around eating last however. This enjoyment can be increased when meals are made into a special time of relaxed togetherness.

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* Acronyms:
LBD: Lewy body dementia
PlwD: person living with dementia
PlwLBD: person living with LBD
DLB: dementia with Lewy bodies
PDD: Parkinson's disease with dementia
MCI: mild cognitive impairment
MCI-LB: the form of MCI that precedes LBD
BPSD: behavioral and psychological symptoms of dementia

For information about Lewy body disorders, read our books:
A Caregivers’ Guide to Lewy Body Dementia
Managing Cognitive Issues in Parkinson's and Lewy Body Dementia

Helen and James Whitworth are not doctors, lawyers or social workers. As informed caregivers, they share the information here for educational purposes only. It should never be used instead of a professional's advice.