In plain English
Psychotic symptoms in dementia, hallucinations and delusions, are common, often treatable and rarely dangerous. They are particularly prominent in Dementia with Lewy Bodies. Most respond to non-pharmacological approaches first.
What we mean
- Hallucinations: perceiving something that is not there. Visual is commonest in dementia; auditory, tactile and olfactory occur but are less common.
- Delusions: fixed false beliefs not amenable to reasoning. Common themes include theft, infidelity, abandonment, and misidentification of family members or the home.
- Misperceptions: misinterpretation of real stimuli (a coat hanger seen as a person, a shadow seen as movement).
How common
Around 20 to 40 per cent of people with Alzheimer's Disease experience hallucinations or delusions at some point. In Dementia with Lewy Bodies, visual hallucinations are a core feature and present in around 75 per cent of cases.
Common themes
Visual hallucinations
Often well-formed: people, children, animals, sometimes recurring characters. May not be distressing for the person, particularly in Dementia with Lewy Bodies.
Delusional misidentification
Capgras syndrome (a familiar person is "an impostor") and reduplicative paramnesia (the house is "a copy" rather than the real one) are well-recognised. Distressing for both the person and the family member affected.
Persecutory beliefs
Theft is the commonest theme. Often relates to misplaced items.
Phantom boarder syndrome
Belief that other people are living in the house. Often benign but can be unsettling for carers.
Auditory hallucinations
Less common than visual. Often non-distressing voices.
Why they happen
Several mechanisms contribute:
- Pathology in visual association cortex and limbic areas (especially in Dementia with Lewy Bodies);
- Sensory impairment (uncorrected vision or hearing);
- Delirium from infection, dehydration, medication;
- Sleep disturbance and dream intrusion;
- Cognitive failure to interpret real stimuli correctly.
What to do
First, look for treatable contributors
- PINCH-ME checklist (pain, infection, nutrition, constipation, hydration, medication, environment);
- Check vision and hearing aids;
- Review medication for hallucination-promoting agents (some anti-Parkinson's medicines, opiates, anticholinergics);
- Treat any acute Delirium urgently.
Non-pharmacological response
- Do not argue or deny; acknowledge the feeling (Validation Therapy);
- Improve lighting (poorly lit rooms produce more visual misperceptions);
- Reduce visual clutter and busy patterns;
- Maintain familiar environment;
- Treat anxiety with calming routine;
- Music, gentle reminiscence, distraction.
Pharmacological treatment
Where symptoms are distressing or pose a risk despite non-pharmacological approaches:
- Optimise Cholinesterase Inhibitor: often reduces hallucinations, particularly in Dementia with Lewy Bodies;
- Add Memantine in moderate to severe disease;
- Antipsychotic medication only as a last resort, under specialist supervision. See antipsychotic prescribing;
- In Dementia with Lewy Bodies, typical antipsychotics (Haloperidol) are contraindicated. Quetiapine or specialist Clozapine where antipsychotic medication is essential.
When to seek urgent help
- Sudden new psychotic symptoms (suggests Delirium): same-day GP, NHS 111 or 999;
- Aggression or safety risk;
- Severe distress to the person.
For Carers
Being misidentified as an impostor (Capgras) is one of the most painful experiences in dementia caring. It does not mean the relationship is lost; it reflects specific brain changes. The Alzheimer's Society and Dementia UK Admiral Nurses provide specific support for this and similar challenges.
Frequently asked questions
Should I tell my parent they are hallucinating?
Generally no. Arguing rarely changes the experience and often distresses. Validation of the feeling and gentle redirection usually work better.
Why does my parent think I am someone pretending to be me?
Capgras syndrome reflects specific brain changes in dementia, particularly in Dementia with Lewy Bodies. It is not personal and does not mean the relationship is lost. Other family members or a different room sometimes help.
Should we treat with antipsychotic medication?
Only where symptoms are severe or pose a risk and non-pharmacological approaches have failed. Specialist input is needed, particularly in Dementia with Lewy Bodies.
Will the hallucinations go away?
Some are episodic and settle with treatment of contributors. Others are persistent. Optimising Cholinesterase Inhibitor often helps, particularly in Dementia with Lewy Bodies.
Are hallucinations always frightening?
Not always. In Dementia with Lewy Bodies, many visual hallucinations are non-distressing. The person may even enjoy seeing children or animals. Treatment is needed only if they distress or pose a risk.
References
- NICE NG97 recommendation 1.7.
- Ballard CG et al. Psychiatric symptoms in dementia. Dialogues Clin Neurosci 2009.
- McKeith IG et al. Diagnosis and management of Dementia with Lewy Bodies. Neurology 2017.
- British Association for Psychopharmacology guidelines on dementia.