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Brain tumour personality changes

Brain tumour personality changes can sometimes occur in people who have been diagnosed. They can range from a lack of motivation to irritability and even, sadly, aggression. And, they can have multiple causes. But, not everyone who is affected by a brain tumour will experience personality changes. 

We’ll look closer at brain tumour personality changes on this page, discussing:

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Can a brain tumour change your personality?

Sadly, brain tumours can cause personality changes. In fact, 1 in 3 people we spoke to had experienced personality changes caused by a brain tumour or its treatment. 

However, it’s important to remember that not everybody who is affected by a brain tumour will experience personality changes.

For those who do, the symptoms and severity can differ from person to person. So, you may not have the same problems as someone with a similar diagnosis and treatment plan.

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What personality changes could a brain tumour cause?

Our brains control every aspect of who we are, what we think and how we feel. It’s perhaps not surprising then, that a brain tumour or its treatment can cause changes to someone’s personality or behaviour. 

Brain tumour behaviour and personality changes can include: 

  • irritability or aggression
  • confusion and forgetfulness
  • apathy (lack of interest and motivation)
  • depression and flattening of emotion
  • loss of inhibitions or restraints and behaving in socially or culturally unacceptable ways
  • anxiety
  • mood swings or extreme moods
  • difficulty planning and organising
  • difficulty identifying emotions in yourself and others.

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We know that, sadly, some people in our community have seen changes in their loved ones that have led to them being violent or aggressive, although this is rare. 

But, if you feel you’re at risk of abuse, remember there’s help and support available, including police response, online support, helplines, refuges and other services.

You are not alone!

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What causes brain tumour personality changes?

Simply knowing there’s a reason you or somebody you know is acting differently can be a huge relief for some people and help them begin to cope emotionally. With that in mind, we’ll look into the main factors that cause brain tumour personality changes.

Brain tumour behaviour and personality changes can be caused by:

Location of the tumour

As a brain tumour grows, it puts pressure on the healthy brain cells around it. This can affect the function, process or part of the body controlled by that area of the brain. 

Personality changes are most common when a tumour is located in the frontal lobe, which controls your personality and emotions. It also controls our ability to regulate our behaviour and restrain ourselves, so tumours that develop in the frontal lobe can cause behaviour that’s considered socially innappropriate.

Personality changes are also common when a pituitary tumour causes the pituitary gland to over- or under-produce hormones. This can affect your emotions and cause changes in your sex drive.

Larger tumours can have a greater effect on personality, as they generally affect a greater area of the brain. However, even a small tumour in a key structure of the brain can have a significant impact.

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Another possible reason for personality changes is swelling in the brain, also known as oedema. This can be caused by the tumour itself or its treatment, including surgery, radiotherapy and chemotherapy.

Grade 1 and 2 brain tumours often cause less swelling than grade 3 and 4 tumours, because they grow more slowly, giving the brain more time to adapt around the tumour. 

Swelling that occurs as a direct or indirect result of treatment usually passes gradually as you recover. Often personality changes will pass when the swelling does.


Confusion and mood swings can also be the result of medication or a combination of medications interacting. Some medications, like anti-depressants, can cause further personality changes. 

Although steroids help reduce swelling and lessen personality changes, they can also cause anxiety, irritability and mood swings. A small number of people may experience steroid-induced psychosis.

You should speak to your healthcare team if your medication is causing unpleasant side-effects, as they may be able to alter your medication. You should never stop taking your medication without consulting healthcare professionals.

The emotional impact

Personality changes can also simply be a natural reaction to receiving a brain tumour diagnosis or its impact on quality-of-life. This can have a huge effect on someone’s mood and behaviour.

Similarly, coping with many of the side-effects of a brain tumour or its treatments can drastically alter someone’s mood.

Treatment and frequent journeys to medical appointments, can also dramatically lower energy levels. So it’s common for people to become less active than before.

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Free counselling

If you need to talk, we’re here for you. We offer free sessions to help you cope.

Coping with personality changes due to a brain tumour

Managing personality changes will depend on what’s causing them. Often it can help to talk to people who have experienced something similar and find out what helps them.

If swelling around the brain is causing the changes, steroids can be prescribed to help reduce the effect of the swelling. Hormone replacement therapy (HRT) can be used to help when personality or behaviour changes are caused by a tumour affecting the pituitary gland. 

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Tips from our community

“I try to keep a diary of my partner’s behaviour, so I can remember everything I need to tell the consultant at appointments.”

“I was so angry all the time and it’s not me. My local hospice group taught me you have to mourn the old you and embrace the new me.”

“Neuropsychology appointments have helped my partner find ways of diffusing a situation before it blows up. They’ve also learnt how to deal with an outburst, if they can’t stop it.”

“We started using a traffic light system at home, so my partner could help me understand how they’re feeling without having to explain to me. They put up a green card on a good day, orange if they’re feeling anxious or tired and a red card if it’s a bad day and they’re feeling irritable.”

Join one of our Online Support Communities for more tips about coping with a brain tumour diagnosis, from people who truly understand what you’re going through.

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Frequently asked questions

Some people are aware of their personality changes, but some people aren’t or they may not have full awareness. 

For example, someone may be aware they’re now less patient and have a shorter temper, but not be able to link the cause and the effect. Some people are aware they are behaving in an inappropriate manner, but will be unable to stop themselves.

This can be a difficult question to answer as it depends on what aspect of your tumour or treatment has caused the personality changes you are experiencing. 

The change could be permanent, especially if it’s caused by physical damage to the brain, for example, as a result of surgery or radiotherapy. In addition to this, if a person’s tumour continues to grow, personality changes may become more pronounced or other changes in the personality may begin to appear.

For many people, medication can help with personality changes or they may fade as you recover from treatment. If the change is due to the emotional impact of living with a brain tumour, psychological support can help.

There are many strategies to help you and your loved ones cope better with personality changes, whether you’re experiencing them temporarily or permanently.

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Download our personality changes factsheet

Personality changes and brain tumours – PDF

Download our information about personality changes and brain tumours in a printable format.

If you have further questions, need to clarify any of the information on this page, or want to find out more about research and clinical trials, please contact our team:
Support and Information Services
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A member of our Support & Information Team provides support over the phone to somebody affected by a brain tumour diagnosis

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