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

When someone with dementia cannot explain what they are feeling or why they are upset, behaviour often becomes their way of communicating.

Responding can feel impossible when you do not know what the behaviour means. 

The following principles can help and are described in more detail below:

1. Consider behaviour as a form of communication

2. Try and understand what might be triggering the behaviour

3. Ensure daily routines reduce the risk of causing  stress and distress

4. Respond with care and insight rather than reacting

Behaviour changes in dementia are often signs of underlying stress or distress. Acting like a detective can help you spot the triggers.

Consider:

• Pain, hunger, thirst, or infection

• Too much noise, clutter, or activity

• Changes in routine

• Certain people or environments

Tools like the PIECES or ABC approach can help identify patterns.

Aggressive or angry behaviour can occur in dementia, often linked to fear, confusion, pain, or distress. While calm communication, giving space, and reducing stimulation can sometimes help, personal safety must always come first. If behaviour escalates, you feel unsafe, or there is a risk of harm to you, others or the person with dementia then, take steps to protect everyone concerned and call the police or emergency services immediately, making it clear that the person has dementia. You should also seek urgent medical advice immediately after any serious incident or where aggression is ongoing, as this may indicate pain, infection, medication issues, or an urgent need for reassessment and additional support.

Busy environments can overwhelm someone with dementia. Noise, crowds, and clutter can be over-stimulating or difficult to process and increase agitation or distress.

A calm, familiar setting helps reduce confusion and anxiety. A predictable daily routine provides comfort and a sense of control when much else can feel uncertain or stressful.

Caring for someone whose behaviour has changed can feel isolating. You may feel embarrassed, angry, or ashamed, and then guilty for feeling that way.

These reactions are normal.

Support matters. Talk to others who understand, whether that is family, professionals, or peer support. You cannot pour from an empty cup. Looking after your own emotional wellbeing is not selfish, it is essential.

Respond with patience
Stay calm, even when you are tired or frustrated. Behaviour is driven by confusion, not choice.

Use distraction rather than confrontation
Redirect attention with simple tasks, music, movement, or familiar activities. 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

• Respect personal space

• Approach from the side rather than face on

• Move slowly

• Be friendly

• Smile and keep your tone gentle and soothing

If someone with dementia finds conversations or situations difficult, they will often look to you for a hint or cue 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 and this can lead to agitated or angry behaviour. 

Do not argue
If they believe something untrue, correcting them often increases distress. Focus on feelings, not facts.

Explain as you go
Unexpected actions can feel frightening. Talking through what you are doing can help reduce anxiety.

Medically reviewed by Dr Jackie Gray, July 2026