If you are caring for a person with dementia, you may have noticed they might have become more agitated and frustrated of late. They may be subject to mood swings and may display anger or aggression – seemingly for no apparent reason. You may have accepted that this is simply the case and learned to modify your own behaviour around them to create less conflict (by not correcting them for instance), but it can be helpful to know why this is happening.

To understand more about the causes behind challenging behaviour, it can be useful to learn a little about the brain and how it functions. The brain is divided into four sections, called ‘lobes’:

  • The frontal lobe controls thinking, memory, behaviour and movement.
  • The occipital lobe controls sight and as the condition develops, the person can struggle to recognize subjects and objects (and may also suffer from hallucinations).
  • The parietal lobe controls language and touch.
  • The temporal lobe controls hearing, learning and feelings.

Other areas of the brain that are affected by dementia include the hippocampus (which date stamps and logs memories), and the amygdala (which processes emotions and records reactions).

When you see how the different lobes influence our abilities, and you appreciate how they need to work together to perform complex tasks, you can start to understand why dementia can have such an impact on a person’s behaviour and mood.

Just a few reasons why a person might become frustrated, upset or angry could be that they can no longer control or understand their emotions, or they can no longer communicate discomfort or pain to you. The first step to caring for someone with dementia when they get angry is to accept it is very often not their fault.

In the earlier stages of dementia, the person’s short-term memory will suffer first, so the person will struggle to remember recent events or conversations, including what they had for breakfast that day or whether or not they went to the shops. Long-term memory will deteriorate in the later stages of the disease.

The Bookcase Model is an analogy used to describe how dementia might affect a person as the condition develops. The explanation was devised by a Dr Gemma Jones. It’s a good way to explain dementia. Picture a bookcase filled with books. Each of those books represents a skill or a memory that a person has gained. In the top shelf are most recent memories (what they had for lunch for example), the next shelf down may contain less recent memories such as events in the past few months or year, such as where they went on holiday. On the third shelf, would be earlier decades of memories of their earlier life.

When the person has dementia, the bookcase starts to move. Books begin to fall out. The ones that tend to fall off first are the ones on the top that relate to short-term memory. As the condition progresses, the person may begin to lose books on the subsequent shelves and may end up with what they think are most recent memories which are actually from an earlier decade or life stage. As the condition gets worse, more books will fall off the shelf. The person will begin to think they are much younger and living their life in the forties, fifties or sixties.

The best way to communicate with a person in the later stages of a person’s dementia is to do it in an emotional way, to help them feel good, loved, and secure in that moment. They will want to feel loved and safe. Tell them you’re there for them, hold their hand or hug them if they are happy for you to do this and reassure them regularly.

Things not to do with a person with dementia:

  • Don’t wrap them up in cotton wool and make them feel helpless
  • Don’t talk to them like they are a child, this is called ‘infantilisation’
  • Don’t outpace them – this means acting or talking to them at a pace that is too fast for them – don’t say too much at once or rush around their house. Break information or tasks down into bite-sized chunks

Ultimately, when you understand what is going on in the brain and why it’s affected by dementia, it’s easier to manage the symptoms and care for your loved one.





  1. My husband will get so mean, but then it can change and he will be himself. he repeats himself all the time, says things he would never say before. He is totally upsessed with dirty dishes in our sink. Things has been changeing so much with him that our sons say they can even see in his eyes with his thinking is really getting messed up, Sometimes he scares me. He is 66 and I am 65. we have been married for 40 yrs. This has been coming on for several years. Is there something more I can do to help him,

    • I am sorry to hear about your husband. In terms of what you can do to help, I would say when he gets obsessed with the dishes or says things you’re not sure about, don’t challenge him. Reassure him the dishes will be dealt with, don’t argue or correct him as this could further increase frustration. I don’t know if your husband is on any medication? If so, how long has he been on it as it may be worth him seeing the GP and having his medication reviewed. Perhaps the dosage or type of medication might need to be changed.

      Otherwise, I’d generally say just reassure him you’re there for him, and if he gets very angry, try not to respond. Give him space if it’s safe to leave the room as you may find he will calm down very quickly. My mum had vascular dementia and when she got angry, she would calm down quickly. Things were usually forgotten within five minutes, so really she just needed space.


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