Changes in perception and hallucinations in dementia

Our senses – hearing, sight, smell, taste and touch – help us understand the world around us.

But in many people with dementia, the brain misinterprets the information from their senses. This can cause ‘changes in perception’, where they experience things differently from other people.

Changes in perception may also be caused by physical changes, such as a person’s sight or hearing getting worse as they get older.

Some people with dementia have hallucinations. This is where they experience something that is not really happening, like hearing voices (auditory hallucinations) or seeing things that aren’t there (visual hallucinations). Visual hallucinations are more common in people with Lewy body dementia.

Is a hallucination the same as a change in perception?

Hallucinations and changes in perception are two separate things that a person with dementia can experience.

Hallucinations are sensory experiences that appear real to the person but are created by their mind, without any external cause. This causes the person to experience something that is not really happening.

Changes in perception are when a person’s brain misinterprets the information from their senses. This can lead to them misunderstanding the world around them or experiencing reality differently from other people.

Examples of a change in perception

There are five main types of change in perception that can happen for a person with dementia.

Misperceptions

This is when a person mistakenly sees one thing as something else. For example, they may see a reflection in a window and believe there is an intruder in their home.

Examples of misperception include the person having difficulty recognising themself in a mirror, believing that their home is not their home, or believing a stranger is someone familiar.

Misidentification

This is when a person has problems identifying particular objects or people. For example, they may mistake their daughter for their wife.

Capgras syndrome

Capgras syndrome is a type of misidentification where the person wrongly believes that someone familiar or close to them is an imposter. This can occur in Alzheimer’s disease and Lewy body dementia. It is thought to occur in around 6% of people with Alzheimer’s disease and 17% of people with Lewy body dementia.

Confabulation

Confabulation is when the brain unconsciously fills in gaps in memory with misinterpreted and false information that the person with dementia firmly believes is true. Carers sometimes incorrectly believe a person is hallucinating in these situations.

Visuospatial difficulties

This is when the brain has trouble processing information about 3D objects. For example, the person might misjudge depth, speeds or distances. This may affect their driving and their ability to move around safely.

Sight and hearing loss in dementia

Changes in perception can also be caused by physical issues with the eyes or ears. And if a person with dementia has sight or hearing problems, this can cause extra issues with confusion and communication.

Some types of dementia cause vision problems. If you or a person you know are experiencing unexplained problems with sight, hearing or changes in perception, visit your GP to try to find out the cause.

Types of hallucinations that people with dementia can experience

Hallucinations may involve any of the senses. The most common are visual and auditory hallucinations – when a person sees or hears something that is not there. But a person with dementia may see, hear, taste, smell or feel anything as part of a hallucination.

Visual hallucinations

Visual hallucinations are when a person sees something that is not there. Examples of visual hallucinations include:

• flashing lights
• shadows
• people, for example strangers, loved ones or people who have died
• animals

Auditory hallucinations

Auditory hallucinations are when a person hears something that is not really happening. Common examples of auditory hallucinations may include:

• voices: talking, whispering or shouting
• footsteps
• doors banging
• phones ringing
• music

Touch hallucinations

Touch hallucinations, also called tactile hallucinations, are when a person physically feels something that is not there. A person may have the feeling of:

• being stroked
• being kissed
• insects crawling over the body

Taste hallucinations

Taste hallucinations are also called gustatory hallucinations. The person tastes something when there is nothing in their mouth.

Smell hallucinations

Hallucinating smells is also known as olfactory hallucinations. Common smells a person may hallucinate include:

• smoke
• perfume
• food

Why do people with dementia experience hallucinations?

Changes in the brain

Changes in perception and hallucinations are more common in people with dementia as a result of damage to certain areas of the brain. For example, if there is damage to the occipital lobe (the rear part of the brain), which is responsible for processing visual information, the person may have difficulty making sense of what they see around them.

Medication

Hallucinations can be a side effect of many medications, or of combining medications. If the person with dementia you care for is experiencing hallucinations and takes medication, you could talk to their GP to check whether they could be caused by their medicine.

Delirium

Delirium is a sudden state of intense confusion that can cause significant distress. It is common in older people and in people with dementia. It is usually triggered by an underlying medical cause (infection, pain, dehydration etc). Broadly, there are three types:

• hyperactive, which often has fluctuations and can cause restlessness and suspicious ideas
• hypoactive, in which sleepiness is a key symptom
• mixed, which is a mixture of both hyperactive and hypoactive, where a person switches between different symptoms

Hyperactive delirium can cause hallucinations – often visual or auditory and sometimes tactile. These symptoms often occur in people who are in hospital.

Types of dementia that can cause hallucinations and changes in perception

All types of dementia may cause hallucinations and changes in perception, but they are more likely to occur in some forms than others.

Lewy body dementia

Visual hallucinations are more common in Lewy body dementia than other types of dementia. They are often more vivid, realistic and complex and can last for several minutes.

Vascular dementia

Vascular dementia often results from a stroke. When this is the case, the person may experience sight difficulties such as double vision, blurred vision, or partial or total loss of sight in one or both eyes.

Alzheimer’s disease

As it progresses, Alzheimer’s disease can cause loss of peripheral (side) vision.

Does the stage of dementia affect the occurrence of hallucinations?

Hallucinations can appear earlier in Lewy body dementia. However, in other types, such as Alzheimer’s disease, hallucinations are more common during the later stages.

Spotting the signs of hallucinations and changes in perception

It can be difficult to know if a person with dementia is experiencing perceptual difficulties or hallucinations. Signs that this might be happening include:

• saying or doing things that suggest they see or hear things that you cannot
• bumping into things or having frequent trips and falls, as though they are struggling to see the objects around them
• not recognising where they are
• displaying changes in behaviour that may indicate fear or distress
• becoming more socially isolated
• reacting to, or looking startled by, things that you cannot see
• muttering under their breath, or speaking as if they are responding to something you cannot hear
• plucking or picking at their skin as if they itch
• reaching for items but missing them, or putting things down in the wrong place, eg putting a cup down but missing the table
• trying to pick things up out of thin air

Speaking to someone with dementia about hallucinations and changes in perception

Changes in perception and hallucinations can feel very real to the person with dementia and may cause distress. If you believe someone is experiencing them, ask them what is happening or what is worrying them. Listen carefully to their response. If possible, see if you can deal with the cause of their distress, for example by drawing the curtains if they are troubled by reflections in the window.

Talk in a reassuring, slow, soothing way and explain what is happening, but try not to contradict the person. This may make them feel you are dismissing their concerns and increase their distress.

Hold the person’s hand or sit close to them and stroke their arm if they find this reassuring.
If the person wears glasses, check they are wearing the correct pair and that they are clean. If they use a hearing aid, make sure it is working and that the batteries are charged.

Distraction techniques can sometimes help. You could:

• both go into a different room or the garden
• take them to the kitchen to make a drink
• offer them a snack
• change the topic of conversation
• turn some music on
• look at some family photos
• go out for a walk

Talking to a healthcare professional about hallucinations and changes in perception

If the person with dementia is having episodes of distress that become more regular or worsen, make an appointment with their GP. It is helpful to keep a record of the person’s behaviour to show the GP, including:

• any triggers for the change in their behaviour
• the signs and symptoms
• what time of the day the behaviour occurred
• if anything helps to reduce or stop the behaviour

The GP will be able to check for any physical causes that may be treatable, such as, infection, pain or sight and hearing issues. If no cause can be found, they may be able to recommend additional strategies for managing the changes in the person’s behaviour and discuss whether a specialist opinion is needed.

Treatment for hallucinations and changes in perception

Often, there is no specific treatment for hallucinations and changes in perception in dementia. But there are many things you can do to help avoid and manage them.

Managing hallucinations and changes in perception

Ways to avoid visual misperceptions:

• Take the person for regular eye tests
• If they wear glasses, make sure they are clean and fit properly, and that their prescription is up to date
• Cover mirrors or turn them around to face the wall. People with dementia may misinterpret reflections as other people in the house
• Move objects that could be mistaken for a person, such as coat stands, dressing gowns or coats hung on doors
• Prevent reflections from windows with blinds or curtains
• Avoid busy patterns on carpets or tiles
• Try to avoid changes in the levels of the floor, such as from thick carpet to wooden floor, which might be difficult for a person with dementia to see
• Make sure rooms are well lit
• Use contrasting colours to make objects stand out, such as block coloured plates; brightly coloured towels that are easier to see when hanging on a towel rail against the wall; or a coloured toilet seat that stands out from the rest of the bathroom. People with dementia often find it easier to see blue than red
• If the person drives, it is essential that they inform the DVLA (DVA in Northern Ireland) of their dementia diagnosis. If they are allowed to continue to drive, try to go out in the car with them on a regular basis to check whether it is safe for them to drive – for example, if they are judging speeds and distances correctly

Ways to avoid auditory (hearing) misperceptions:

• Take the person for regular hearing tests
• If they wear a hearing aid, make sure it is clean and well maintained, and that the battery is checked regularly
• Speak slowly and calmly to the person
• Face them when speaking
• Turn off background noise such as the TV and radio when speaking to them
• Try to avoid sudden loud noises, such as Christmas crackers, party poppers or fireworks as these can cause shock and fear

Ways to avoid taste misperceptions:

• Take the person for regular dental check-ups. Tooth decay or gum disease can create a bad taste in the mouth, which people with dementia may misperceive as something being wrong with their food
• Make sure the person follows a daily mouth care routine, with support if needed
• Check the person’s dentures, teeth and mouth for signs of soreness, infection or damage and ask whether they have any discomfort
• Be aware that people’s food and drink preferences may change when they have dementia and try to accommodate this – for example, someone may suddenly dislike milk in their tea

Ways to avoid sense of touch misperceptions:

• Look out for excessive scratching or plucking at the skin and try to identify a trigger
• Find out whether there has been a change in medication – itching might be a side effect
• Check if there has been a change in washing detergent or fabric conditioner which may have triggered an allergic reaction or skin sensitivity
• Consider whether the person has an allergy to something else in the environment, such as soap or pet hair
• Assess whether the person is too hot or cold
• Check if their clothing is causing discomfort, for example if cuffs are too tight, fabric is rough or scratchy (eg pure wool) or seams are irritating the skin

Ways to avoid sense of smell misperceptions:

• See if anything in the house is causing a bad smell – for example, the bin, rotten food, a pet litter tray or cage. People with dementia can misperceive bad smells as something worse, such as a gas leak
• Encourage the person to follow a good personal hygiene routine, with assistance if necessary
• Consider using mild washing detergents and fragrance-free toiletries – strong smells may be overwhelming

Antipsychotic medications and dementia

Antipsychotic medications may be able to help with severe or distressing hallucinations. However, as they can have unwanted side effects, they should only be tried as a last resort when other treatments have not worked, and if the person with dementia is a risk to themselves or others.

Antipsychotic medication can create particularly severe reactions for people with Lewy body dementia.

Because antipsychotics increase the risk of stroke and heart attack, the person with dementia will often need to undergo testing such as an ECG (a trace of heart rhythm) and blood tests first. The doctor will discuss the risks and benefits of the medication in each individual case to reach an informed decision.

Sources of support

If you’re concerned about changes in perception or hallucinations in a person with dementia, make an appointment with their GP. They can help to identify and treat any possible physical causes. If the person has a specialist dementia doctor or Admiral Nurse, they can give you advice on how to help with these difficulties.

If you need advice, please call our free Dementia Helpline on 0800 888 6678 (Monday-Friday 9am-9pm, Saturday and Sunday 9am-5pm, every day except 25th December), email helpline@dementiauk.org or you can pre-book a phone or virtual appointment with an Admiral Nurse.

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