How does dementia change a person's behaviour?

Information for carers about behaviours a person with dementia might develop.

As a person’s dementia progresses, they may begin to behave in ways that other people find difficult to understand. This can be one of the most difficult aspects of living with dementia, both for the person with the condition and those around them.

Changes in behaviour are sometimes the first sign that someone has dementia. For some people, they can come on gradually and can be hard to recognise at first. For others, the changes can be more sudden.

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As dementia progresses, you may see more changes in the person’s behaviour and find this difficult to manage. Looking at their causes and identifying the person’s needs can help.

When a person with dementia starts to behave in ways that seem out of character, some people may assume this is a symptom of the condition itself, which isn’t always the case. It’s important to see beyond the behaviour and think about what may be causing it.

There may be specific reasons why the person with dementia is behaving differently, such as:

  • their frustration or fear about how dementia is affecting them (such as memory loss, or language problems)
  • their mental and physical health
  • their problems with orientation – for example, not knowing which year, month or time of day it is, or not recognising familiar places
  • the amount and quality of contact they have with other people
  • their physical surroundings – for example, if the room is too dark the person may become confused and distressed because they can’t work out where they are
  • a sense of being out of control, frustration with the way others are behaving, or a feeling that they’re not being listened to or understood.

Dementia can affect a person’s personality and habits, which may lead to changes in behaviour. For example, they may no longer be able to do things they enjoy or follow their interests without help, or they may experience symptoms of depression.

Knowing the person – how they react to and deal with things, their preferences, routines and history – can help when it comes to supporting them. For example, if the person has always been impatient or anxious, they may be even more so now that they have dementia.

Types of behaviour

The person’s response to different needs means their behaviour may change in a number of ways. Some of the most common changes are listed on this page.

You may have heard these called ‘challenging behaviours’. However, we refer to them as ‘behaviour that challenges’ instead. It’s important to remember that the person isn’t trying to be difficult. The behaviour can be just as challenging for them as for the people supporting them.

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