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Why Does Dementia Cause Hallucinations?

What are hallucinations and how do they affect people living with dementia and their families?

A hallucination is a sensory experience of something that appears real but is simply created in our mind. Hallucinations are commonly experienced by persons living with dementia although exact estimates of their frequency differ. The frequency of hallucinations may also depend on the type of dementia. For example, as many as three quarters of persons diagnosed with dementia with Lewy bodies, and up to two-thirds of those with Parkinson’s Disease dementia, may at some point experience hallucinations compared to only about one fifth of individuals affected by Alzheimer’s disease.

Hallucinations in individuals with dementia can cause fear and anxiety in those experiencing them as well as their loved ones. They are also related to worsening cognitive function, and further undermine the affected person’s ability to perform their usual activities of daily living (ADLs) such as grooming, using the bathroom and so on. Deterioration in ADLs in itself undermines quality of life of persons with dementia.

Hallucinations may affect all five of the senses (sight, sound, smell, taste, and touch). For example, a person might see an image or object that isn’t real. According to the Alzheimer’s Society other types of hallucinations may include:

  • Hearing things, such as footsteps or voices
  • Smelling things, perhaps perfume or cigarette smoke
  • Physically feeling things, like insects crawling over the skin or someone touching you
  • Tasting things, like a metallic taste in the mouth

Why might someone with dementia experience hallucinations?

There may be different reasons for hallucinations in individuals living with dementia. Although the complex changes that occur in the brains of these persons may trigger such sensory experiences, they can also happen for many other reasons, including:

  • Trouble seeing or hearing: Poor light, background noise, or poor eyesight or hearing make it hard to see and hear well.
  • Illness: Fever, migraine, or infection can affect how the brain handles information from the senses.
  • Medications: Many drugs (both prescription and over-the-counter medications) can lead to hallucinations in susceptible individuals.
  • Mental illness: If someone has a history of serious mental illness, their hallucinations may be related to it.
  • Confusion (delirium): Certain illnesses and medications sometimes make someone more confused. This can make them more likely to experience hallucinations.

Recognising and verifying signs of hallucinations in those living with dementia

It can be difficult to know when a person with dementia is experiencing perceptual difficulties or hallucinations. It can appear that a person is experiencing hallucinations where there may be some other explanations. For instance, if the person is claiming to have a strange or unpleasant taste in their mouth it could be that they’re overdue a dental check-up or, if they wear dentures, that they are causing discomfort or are ill-fitting. It could even be due to the particular brand of toothpaste that they’re using. When it comes to visual or auditory perception, the person may need a hearing or sight check and in addition, it should be confirmed that any equipment they use, such as glasses or hearing aids, are clean and functioning. As pointed out by Dementia UK, practical actions such as these constitute simple ways to help prevent misperceptions and hallucinations.

In such circumstances, it may be helpful for you to face the person and explain that you’ll go first to show them that it’s safe. Reassuring the person while holding their hands and slowly walking backwards will hopefully help them to begin crossing the perceived obstacle with you. Maintaining eye contact and vocally reassuring the person should help them to trust what you’re saying and encouraging them as you progress should mean that the incident will be quickly forgotten. It is important to explore potential reasons for different signs of hallucinations and to seek medical advice where necessary.

Treating hallucinations in individuals with dementia

Regular hallucinations are something that should be checked by the person’s GP, and urgent medical attention should be sought if the hallucinations are involving several senses at once. Treatment of hallucinations depends on their cause (see different reasons listed above). If a new medical problem (e.g. a urinary tract infection) is thought to be the reason, then that’s what should be treated. If the problem involves the person’s medications, their GP may try to adjust these to see if it has any effect or suggest other things to try instead that may help to reduce the hallucinations. For example, if the hallucinations are thought to be caused by the progression of Alzheimer’s disease or another type of dementia, the GP may suggest antipsychotic medication if they feel it is appropriate.

The GP will want to know if anything triggers the changes in the person’s behaviour, what the signs and symptoms are, what time of the day the behaviour occurred, for how long and so on. As suggested by Dementia UK, family carers are in a unique position to monitor signs of hallucinations and inform the GP if required. However, because of the complexity of hallucinations and other behaviours in individuals with dementia, as well as the fragility of the elderly population, treatment with drugs appears to be limited in terms of safety and efficacy, and nonpharmacological therapies are often considered a better first choice.

Responding when someone with dementia experiences hallucinations

The first step is to determine whether the hallucination is troubling the person experiencing it. Not all hallucinations are necessarily scary or causing distress, some may generate pleasant experiences and may not need to be responded to. Sometimes carers need to understand and accept the changes that occur in their loved ones as their dementia progresses. However, if the hallucination is upsetting them or causing them to do something unsafe, then it’s time to quickly step in to provide comfort or redirect to a safe activity. outlines 10 effective ways to respond to dementia hallucinations. For instance, it’s important to avoid feeling angry or dismissive when the person experiences hallucinations, as they will appear very real to them and your reaction will only upset and confuse them more. It’s understandable that loved ones may feel frightened or frustrated when the person claims to hear or see something that others can’t, however, they may mirror other’s reactions which could make things worse.


According to the Alzheimer’s Society, there are a number of things people can try that may help when someone is experiencing a hallucination. These include:

  • Calmly explaining what is happening, but not arguing with them if they are unable to understand, as “trying to convince someone that they are mistaken can lead to more distress.”
  • Keeping the person company while they go through the hallucination and asking them to try and describe it to you may help to reduce the experience.
  • If the hallucination is being brought on by a particular place, gently trying to remove them from that place, if it’s practical and safe to do so, may help.
  • Checking the person isn’t hungry, thirsty or in discomfort, as “dehydration, constipation or infection can lead to delirium, a cause of hallucinations.”
  • As before, distraction can be helpful, so suggest something that the person enjoys doing instead.

How Helping Hands can support those with dementia and their families?

When you or someone you love is living with dementia it can be difficult to understand all the changes that are taking place, which is why it is important to have a dementia specialist home care organisation providing any care that you need. Helping Hands’ dedicated and compassionate carers will ensure that you are fully cared for in the home you love, while making sure that your loved ones also receive the emotional support they need.

When receiving dementia care it can be highly beneficial to remain in your own home, as being in familiar surroundings, amongst precious people, pets and possessions can help to reduce confusion and anxiety and help you to live well with your condition. We have been supporting people living with dementia in their own homes for over 30 years, meaning that we’re highly experienced in how best to care for people with Alzheimer’s, Vascular, Lewy Body or one of the other over 100 different types of dementia.

Helping Hands are regulated by the Care Quality Commission and Care Inspectorate Wales and thanks to our fully managed service you can always have confidence in us to consistently deliver the very highest standards of care.

About The Author

This article has been written especially for Helping Hands and comes from Snorri Rafnsson’s work at the Geller Institute of Ageing and Memory, School of Biomedical Sciences at the University of West London.

Dr. Snorri Bjorn Rafnsson BSc (Hons.), MSc (Edin), PhD (Edin), PGCHE, FHEA, FRSPH (UK) currently serves as Associate Professor of Ageing and Dementia in the Geller Institute of Ageing and Memory, School of Biomedical Sciences at the University of West London.

His research combines an interest in epidemiology and social gerontology.

References and further information:

Page reviewed by Snorri Rafnsson, Associate Professor of Ageing and Dementia in the Geller Institute of Ageing and Memory on October 6, 2021