Hallucinations and false ideas

People with dementia sometimes experience a range of conditions in which they do not experience things as they really are.

Although hallucinations and delusions are imaginary, they seem very real to the person experiencing them and can cause extreme anxiety, and even panic.

What are they?


Hallucinations are sensory experiences that cannot be verified by anyone other than the person experiencing them. Such experiences may include any of the senses, but the most common are visual and auditory hallucinations – the person sees or hears something that is not there. Voices may be heard, people may be seen who are not present, or strange and frightening noises may be heard.


Paranoia is characterised by unrealistic beliefs, usually of either persecution or grandeur. People with dementia may believe that others are out to get them, or that they have superhuman powers. People with dementia sometimes become quite suspicious, accusing others of stealing things and hoarding or hiding things because they believe someone is trying to take their possessions. One common accusation is that the person’s partner is being unfaithful. Such ideas may lead the person with dementia to become fearful and resistant to attempts to care for them.


Delusions are ideas that are not based on reality, but which are thought to be true by the person with dementia. Their content can often be centred on people stealing money or other possessions, or they may have fixed ideas about people intending to harm them.


People with dementia can misidentify other people or themselves. Sometimes they do not recognise their partner as being the person they have known. At other times they may think their reflection in the mirror is another person and be frightened, 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 has received. Examples of this include failure to recognise a partner or the house in which the person lives.

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 create an interpretation in which someone or something else is blamed. This is understandable when they may live in a world with no memory of recent events, where things “disappear”, explanations can be forgotten and conversations do not always make sense. 

Factors which may cause behaviours to change

  • Sensory defects such as poor eyesight or poor hearing
  • 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
  • Unfamiliar caregivers
  • Disruption of familiar routines
  • Misinterpretation of environmental cues often a result of forgetting to use a hearing aid or glasses
  • Sensory overload because of too many things going on at once.

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 the Aged Care Assessment Teams (ACAT) or for specialised psychiatric assessment. 

Drug treatments

Medication will sometimes help to control delusions or hallucinations in people with dementia, and occasionally will help to control misidentification syndromes. However, many of the anti-psychotic medications used to treat these disorders have side effects such as stiffness, shakiness or drowsiness. Newer anti-psychotic medications have fewer side effects but can still cause drowsiness. Sometimes, where delusions and hallucinations are causing a major problem, a trial of a drug treatment may be appropriate. 

What to try

  • Do not argue. It is better to acknowledge that the person may be frightened by the delusions and hallucinations.
  • Do not scold the person for losing objects or hiding things.
  • Investigate suspicions to check their accuracy.
  • Attempt to distract the person if possible.
  • Try to respond to the underlying feelings which may be at the bottom of the statements which the person makes.
  • Distractions which may help include music, exercise, activities, conversations with friends and looking at old photos.
  • Physical contact may be reassuring, but be sure that the person is willing to accept this.
  • Try to 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.
  • Try to maintain consistent caregivers and a consistent routine.
  • Try to learn the person’s common hiding places.
  • Keeping a diary may help to establish whether these behaviours occur at particular times of the day or with particular people. Identifying such causes may help you to be able 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.
  • Do not take the accusations personally and be aware that the person is not able to control this behaviour.

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 friend, a professional or a support group.

Keep in mind that 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.