Hallucinations and False Ideas

People with dementia sometimes do not experience things as they really are. That is, they have hallucinations and/or delusions. These seem very real to the person experiencing them and can cause extreme anxiety, and even panic.

Information Sheet

What are they?

Hallucinations are sensory experiences in which a person can hear, see, feel, taste or smell something that is not there; it cannot be verified by anyone other than the person experiencing them. The most common are visual hallucinations –the person sees something not there – and auditory hallucinations – the person hears something that is not there. For example, they may see non-existent people, lights or bugs or hear strange voices and frightening noises.

Delusions are ideas that are not based on reality, but which are thought to be true by the person with dementia. For example, they may think they have to fetch the children from school or milk the cows.

Paranoia is characterised by delusions, of persecution or grandeur. People with paranoia may believe that others are intending to harm them or that they have special powers. They may become suspicious, accusing others of stealing their possessions, and so they hoard or hide things. A common accusation is that the person’s partner is being unfaithful. Such ideas may lead the person with dementia to become fearful or angry and resistant to attempts to care for them.

People with dementia can misidentify other people or themselves. Sometimes they do not recognise their partner as being the person they know. At other times they may think their reflection in the mirror is a frightening stranger in their house or think that voices on the radio or television are from people in the room with them.

What causes hallucinations and false ideas?
Dementia may cause the person to lose the ability to recognise things because the brain does not accurately interpret the information that it receives. The person’s response is then based on their faulty understanding of the situation. Problems with memory, which occur in dementia, may lead to suspiciousness, paranoia, and false ideas. If people with dementia are unaware that their memory is poor, they will often explain what they have forgotten by blaming someone else. This is understandable if they live in a world with no memory of recent events, where things “disappear”, information is forgotten, and conversations do not make sense.

Factors which may cause behaviours to change:

  • Sensory defects such as poor eyesight or poor hearing (and forgetting to use a hearing aid or glasses)
  • Side effects of some medications
  • Psychiatric illness
  • Unfamiliar environments
  • Inadequate lighting, making visual clues less clear
  • Physical conditions such as infections, fever, pain, constipation, anaemia, respiratory disease, malnutrition, dehydration (delirium).
  • Unfamiliar caregivers
  • Disruption of familiar routines
  • Sensory overload because of too many things going on at once.
  • Memory distortion causing a person to be ‘living in a different time frame’

Where to begin

Arrange for a medical check-up to eliminate the presence of other physical or psychiatric problems, and to check the effects of medication. The doctor can also arrange for referrals to Health of Older People or Mental Health Services for Older People.

What to try

  • Acknowledge that the person is experiencing delusions and hallucinations that may be frightening without saying that you believe them yourself.
  • If a person appears to be losing objects or hiding things, suggest that you search together.
  • Learn the person’s common hiding places
  • Investigate suspicions to check their accuracy (they may be true)
  • Distract the person if possible, for example with music, exercise, activities, conversations with friends and looking at old photos.
  • Respond to the underlying feelings which may be at the bottom of the person’s symptoms e.g. someone who does not recognise their house and is searching for their own home, may feel insecure.
  • Physical contact may be reassuring, but be sure that the person is willing to accept this.
  • Maintain a familiar environment. If the person has to move, take some familiar things from the previous residence.
  • Increase lighting in the home and use night lights
  • Cover up mirrors if necessary.
  • Reduce noise that could be misinterpreted.
  • Maintain consistent caregivers and a consistent routine. Keeping a diary can establish whether these behaviours occur at certain times of the day or with particular people. Identifying such causes may help you to make changes to overcome the difficulties.

Keeping a diary can establish whether these behaviours occur at certain times of the day or with particular people. Identifying such causes may help you to make changes to overcome the difficulties.

  • If possible, keep a spare set of things that are often mislaid such as keys, purse or glasses.
  • Some hallucinations and false ideas can be ignored if they are harmless and do not cause the person to become agitated


Medication can sometimes help to control delusions, hallucinations, or misidentification syndromes in people with dementia. However, many of these anti- psychotic medications have side effects such as stiffness, shakiness or drowsiness and can increase confusion, falls and the risk of stroke. Sometimes, where delusions and hallucinations are causing a major problem or significant distress, a trial of a drug treatment may be appropriate.

Remember that the person’s behaviour is caused by a brain condition and be aware that the person is not always able to control their behaviour.


The confusion of dementia may result in a person getting details mixed up and fabricating incidents from fragmented memories. The person may for example tell us that “Mum visited this morning” even though Mum passed away several years ago. It is important to understand that confabulation is not lying, but the unintentional effect of dementia. In these situations, it is best for us to join the person in their reality, rather than attempting to correct and point out the truth.

Support for families and carers

Dealing with these behaviours day in and day out is not easy. It is essential that you seek support for yourself from an understanding family member, a professional or a friend.


Feelings of distress, frustration, guilt, exhaustion, and exasperation are quite normal.

Who can help?

Discuss with the doctor your concerns about behaviour changes, and their impact on you. You can also seek support from a Dementia Advisor or join a Dementia support group.