Delusions and hallucinations

Hallucinations and delusions can be symptoms of Alzheimer's disease and other dementias. With hallucinations or delusions, people do not experience things as they really are.

Older man looking worriedly out the window


Hallucinations and delusions are symptoms of Alzheimer's disease and other dementias. With hallucinations or delusions, people do not experience things as they really are.


Delusions are false beliefs. Even if you give evidence about something to the person with dementia, they will not change their belief. For example, a person with dementia may have a delusion in which they believe someone else is living in their house when they actually lives alone.

Delusions can also be experienced in the form of paranoid beliefs, or accusing others for things that have not happened. For example, the person with dementia may misplace an item and blame others for stealing it. Some people with dementia may have the delusion that others are "out to get them." For example, they may believe that their food is being poisoned.


Hallucinations are incorrect perceptions of objects or events involving the senses. They seem real to the person experiencing them but cannot be verified by anyone else. Hallucinations are a false perception that can result in either positive or negative experiences.

Hallucinations experienced by people with dementia can involve any of the senses, but are most often either visual (seeing something that isn't really there) or auditory (hearing noises or voices that do not actually exist). For example, a visual hallucination could be seeing bugs crawling over the bed that aren't actually there. Of course, people also make “visual mistakes,” mistaking a housecoat hanging up for a person, for example, because they can’t see the object clearly. This can happen to anyone, and is not considered a hallucination.

As a rule, if the hallucination is not upsetting, don’t intervene.

Possible causes

  • Sensory changes (hearing and vision diminishes)
  • Medications or physical illness
  • Unrecognized environment or caregivers, inadequate lighting
  • Disruption of routines
  • Removal of items from the person (i.e. money or jewellery)

Tips and strategies

  • Meet with the person's physician to review medications and schedule hearing and vision tests.
  • Seek medical evaluation for illness, infection, bowel impaction, UTI etc.
  • When a person experiences suspiciousness: look for lost articles and remind them where the valuables are stored.
  • Don’t scold for losing or hiding things and keep a spare set of frequently lost items (if possible).
  • Investigate suspicions that might be true.
  • Increase lighting in the room.
  • Do not directly disagree with a false idea.
  • Use physical touch as reassurance.

Example #1

Kate is fearful at night because she sees spiders crawling on her bedroom walls.


  • Tell her nothing is on her walls, such as, “You see, Kate: nothing is there. Go back to bed.”


  • Validate the fear: “That must be very frightening for you.”
  • Do not get angry and argue. This is real to Kate.
  • Check for shadows that could be misinterpreted as spiders and try to remove them (i.e. increase lighting).
  • Distract with music, exercise, playing cards or photos.
  • It may be useful to see if the person has any hearing or vision problems at this time.

Example #2

Josie lives in a long-term care home and is convinced that someone has stolen her purse. She always keeps it in her bedside table and this morning it was gone. She is sure that “new girl with the funny eyes,” as she puts it, took it.


  • Explain no one stole her purse and, just like last time, she lost her bag.


  • Validate Josie's feelings.
  • Try to alleviate the distress (e.g. look for the “stolen” purse and then distract her).
  • Investigate suspicions that could be true. She could be a victim. But if it turns out to be paranoia and the paranoia continues, have similar purses ready as replacements.

More information and resources

Behaviours in Dementia Toolkit by the Canadian Coalition for Seniors' Mental Health is an online library of over 200 free resources to help care partners and health care providers better understand and compassionately respond to dementia-related changes in mood and behaviour.

Delirium Prevention and Care with Older Adults by the Canadian Coalition for Seniors’ Mental Health provides information about the signs of delirium, what causes delirium, and how it can be prevented and treated.

Shifting focus: Guide to understanding dementia behaviour by the Alzheimer Society of Ontario and Behavioural Supports Ontario is meant to help family members, friends and caregivers of people with dementia understand behaviours and actions.