Changes in perception and hallucinations in dementia

Our senses – hearing, sight, smell, taste and touch – help us understand the world around us.  

But in many people with dementia, the brain misinterprets the information from their senses. This can cause changes in perception, where they experience things differently from other people. 

Changes in perception may also be caused by physical changes, such as their sight or hearing getting worse as they get older. 

Some people with dementia have hallucinations. This is where they experience something that is not really happening, like hearing voices (auditory hallucinations) or seeing things that aren’t there (visual hallucinations). Visual hallucinations are more common in people with Lewy body dementia. 

Recognising changes in perception and hallucinations in people with dementia

Signs that someone may be experiencing changes in perception or hallucinations include: 

  • not recognising where they are 
  • bumping into things or having frequent trips and falls, as if they’re struggling to see objects around them 
  • reacting to things other people can’t see 
  • muttering under their breath, or talking like they’re responding to something you can’t hear 
  • appearing frightened or distressed 
  • scratching or picking their skin as if they itch 
  • becoming more socially isolated 
What to do when a person with dementia is experiencing changes in perception or hallucinations

It can be alarming if a person with dementia has changes in perception or hallucinations. These tips will help you to help them. 

  • talk slowly and calmly. Try our tips for better communication 
  • ask what’s wrong. Listen to what they say, and see if you can deal with whatever is making them distressed 
  • explain what’s happening, but avoid contradicting them, as this could increase their distress 
  • it might help to sit with them, hold their hand or stroke their arm 
  • check they’re wearing the right glasses, and/or that their hearing aid is working 
  • try to distract them: you could move to a different room, make them a drink, or go for a walk 
  • think about possible physical reasons for their distress, like constipation, dehydration or an infection. You may want to take them to their GP for a check-up 
Helping prevent changes in perception and hallucinations in people with dementia

The good news is there are lots of things you can do to help people with dementia who are experiencing changes in perception and hallucinations. 

Visual (sight) changes  

  • take the person for regular eye tests 
  • if they wear glasses, make sure they’re clean 
  • make sure rooms are well lit 
  • cover or remove mirrors: the person may mistake reflections for other people 
  • use blinds or curtains to prevent reflections in windows 
  • move objects that might look like another person, like coat stands or dressing gowns hanging on doors 
  • try to avoid busy patterns on carpets or tiles, and changes in floor level (such as from thick carpet to hard flooring): these can be difficult to see and lead to falls 
  • use bright, contrasting colours to help objects stand out against the background, like solid coloured plates, bright towels, and coloured toilet seats (for example, a black seat on a white toilet) 
  • read our advice on making the home safe and comfortable for people with dementia 

Auditory (hearing) changes  

  • take the person for regular hearing tests 
  • if they wear a hearing aid, make sure it’s clean and well maintained, and check the battery regularly 
  • face the person when talking to them
  • speak slowly and clearly 
  • turn off background noise like the TV or radio when speaking to them 

Taste changes  

  • make sure the person follows a daily mouth care routine (e.g. brushing their teeth or cleaning dentures) 
  • take them for regular dental check-ups: tooth decay and gum disease can cause a bad taste in the mouth and make food taste strange 
  • check their mouth, teeth and dentures for signs of damage or infection, and ask if they have any discomfort 

 Changes in sense of touch  

  • find out if their medication has changed: itching can be a side effect of some medicines 
  • check if their washing detergent or fabric softener has changed, causing skin irritation 
  • assess whether they’re too hot or cold 
  • check if their clothes are making them uncomfortable, for example with tight collars or scratchy labels
  • consider whether they might be having an allergic reaction 

Changes in sense of smell  

  • check for bad smells in the home, like the bin, food that’s gone off, or pet litter 
  • encourage them to follow a good personal hygiene routine, with help if necessary 
Getting help with changes in perception and hallucinations

If you’re concerned about changes in perception or hallucinations in a person with dementia, make an appointment with their GP. They can help to identify and treat any possible physical causes. If the person has a specialist dementia doctor or Admiral Nurse, they can give you advice on how to help with these difficulties. 

To help you make the most of your appointment, read our guide to getting the best out of GP and other health appointments.

You could also ring the free Admiral Nurse Dementia Helpline. It’s run by specialist dementia Admiral Nurses who have the time to listen and the knowledge to solve problems.  

The Admiral Nurse Dementia Helpline can be contacted on 0800 888 6678 or by email at helpline@dementiauk.org (Monday to Friday 9am-9pm; Saturday and Sunday 9am-5pm, every day except 25th December). 

Remember, it’s natural to find it hard when you’re supporting someone with changes in perception or hallucinations. Our information on sources of support can help when things feel difficult. 

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Publication date: December 2020
Review date: December 2022