Understanding Behaviour Changes in Dementia

Medically Reviewed by: Dr Jackie Gray, Public Health Expert and Retired GP
(Carents Trusted Reviewer Programme – Last reviewed February 2026)

Most people know dementia affects memory and everyday skills. Fewer realise that behaviour changes in dementia are extremely common and can be signs of stress or distress.

A common technical term for behavioural changes in dementia is Behavioural and Psychological Symptoms of Dementia (BPSD) because these changes often occur alongside personality changes, delusions and hallucinations.  

Dementia behaviour varies depending on:

• The type of dementia

• Which parts of the brain are affected

• How far the condition has progressed

Behaviour changes can occur at any stage.  They are often a response to an underlying problem such as frustration, anxiety or pain so understanding why they are happening can help you and those around you to deal with them more effectively.

Dementia can damage areas of the brain responsible for judgement, emotional regulation, and social awareness. This is why dementia can change someone’s personality so dramatically. A previously calm person may become angry or suspicious. Someone reserved may lose social filters.

The changes occur because the brain is struggling to deal with impulses and emotions.  They are not a reflection of the person with dementia or how they feel about you.

Behaviour changes can be upsetting for everyone involved, including the person with dementia, family members, friends, and carers.

Common changes include:

• Apathy or withdrawal

• Agitation or aggression

• Loss of social filters

• Sexually inappropriate behaviour

• Impulsivity or compulsive habits

These behaviours can be embarrassing, frightening, or exhausting to deal with.They are not deliberate.

Labels like “challenging behaviour” are often used, but those terms suggest intention or choice. In reality, these behaviours are symptoms of a brain that is struggling to process the world properly.  It is often family friends or carers who feel challenged by these behaviours as they struggle to understand and to deal with them

Dementia affects how well someone can process and act on information in order to communicate appropriately and effectively.

The disease can make it difficult for those affected to:

• follow conversations
• respond to questions or instructions
• express themselves, their needs, feelings or concerns
• interpret facial expressions or body language
• respond appropriately to social or emotional cues
• act in ways which are appropriate for different situations
• modify their behaviour

These challenges mean that behaviour can sometimes be used as a form of personal expression. For example, if someone with dementia acts out in an angry or irritated way, it can mean that they feel distressed.

The distressed behaviour might reflect feelings of being frightened, confused, frustrated, or in pain. Similarly, repetitive activities might represent a form of self soothing in the face of anxiety, pain, and confusion.

Understanding that behavioural changes in someone with dementia, can often signal inner confusion, pain, or distress can prompt you to apply some detective skills and consider any explanations or triggers for the behaviour. Consider whether different people, situations, or activities might be contributing.  You might find the PIECES and ABC tool helpful.

Adults living with dementia can find it harder to respond to their environment.  They might become angry, agitated, or frustrated when faced with lots of external stimuli, which makes it harder for them to understand or follow what is going on.  Crowds, clutter, and noise can all be over-stimulating or make life harder.

A quiet and familiar environment can make it easier for someone with dementia to understand and respond to the stresses and strains of everyday life and help them feel more in control. Similarly, a regular daily routine can also provide a source of comfort and promote a sense of predictability, familiarity, and control.

Respond with patience

Be patient, calm and don’t take things personally. A sense of humour can help.

Although it is not easy, it is important to recognise that behavioural changes are due to real difficulties in understanding and responding to situations rather than because the person affected is deliberately trying to be difficult. Remember, dementia affects the brain and the ability to consider and respond to how other people feel.

If someone is agitated then responding with patience and calm is likely to have a soothing effect whereas anger and irritation might make things worse.

If they find conversations or situations difficult, many people with dementia will look to others for hints or cues to help them understand what is going on.  If you appear anxious, agitated or angry then they will pick up on and mirror those emotions with related behavioural changes.

Use distraction rather than confrontation

Repetitive, agitated or potentially harmful behaviours can often be relieved by activities which distract and shift attention. Find ways to substitute the behaviour with other activities such as helping with simple tasks (laundry, housework) or creative pursuits like singing, dancing or craft.

Avoid appearing threatening

Consider how your behaviour can impact others who may be feeling confused or vulnerable.

• Do not invade their personal space
• Help from the side rather than face-on
• Do not argue  – accept that they are right and you are wrong
• Take things slowly, don’t rush or pressurise
• Smile and be friendly
• Explain as you go to avoid unexpected surprises

Medically reviewed by Dr Jackie Gray, July 2026