How can dementia change a person's perception?

People with dementia experience changes in how they perceive things. This includes misperceptions and misidentifications, hallucinations, delusions and time-shifting.

How a person with dementia experiences (or perceives) things often changes as their dementia progresses. Many people with dementia experience changes in how they understand the world around them. This is because in dementia there is damage to the brain, which can cause the person to experience things differently.

Changes in perception include;

These problems can cause the person with dementia to say or do things that do not make sense to others. This can be frustrating, confusing and upsetting for the person, and for carers, especially if the person is experiencing a different reality to yours.

By responding in a supportive way, you can keep up their confidence and help them to cope with the misunderstanding.

How can a carer support a person experiencing changes in perception?

Understanding the problems they may face and giving the right help, support and reassurance can help people living with dementia to feel safe. If you are able to help the person you care for to make sense of the world, you may find it can maintain their wellbeing and sense of self.

Some carers have to deal with these changes on a regular basis. If your caring role is becoming increasing difficult, it may be useful to contact your local authority and request a Carer’s assessment. You could also ask about care packages or respite care if you need a break.

Recognising delirium 

If you notice a sudden change in the person with dementia (over hours or days), it could be delirium, which is a medical emergency. You should make an urgent appointment with the GP or call the NHS 111 telephone service.

Delirium can be triggered by an untreated health condition. Most of the causes of delirium are treatable, such as constipation, dehydration or infections. Delirium can cause people to have hallucinations or delusions, become confused, drowsy, or distressed. 

What is perception?

Information from the sense organs, for example the eyes or ears, travels to the brain. The brain processes this information, to understand it. The brain then analyses it alongside other information already in the brain, such as thoughts and memories and their associated emotions. Then the person becomes aware of what has been sensed (perceived).

How can dementia affect perception?

Dementia can interrupt or slow this process down, which changes how a person understands the world around them. Damage to the eyes or parts of the brain may cause misperceptions, misidentifications, hallucinations, delusions and time-shifting.

For more information on how dementia affects different parts of the brain and the brain’s ability to do things, see Dementia and the brain.

Need more support as a carer?

Changes in perception can be hard to cope with. Read our information for carers.

Looking after yourself as a carer Read our practical guide for carers
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