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Personality changes and brain tumours

1 in 3 people we spoke to had experienced personality changes caused by a brain tumour or its treatment. 

It's important to remember that not everybody who is affected by a brain tumour will experience personality changes.

For those that 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.

What personality changes could someone experience?

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.

    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. 

    These changes can seem even more worrying in the current situation, but it’s important to remember that if this is something you’re experiencing, your safety is paramount and the current social distancing (or isolation) rules don’t apply if you need to leave your home to escape domestic violence.

    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!

    Find out more

    Is your loved one behaving differently?

    People with a brain tumour often behave differently - due to the tumour pressing on their brain or the emotional effects of diagnosis and treatment. Use BRIAN’s quality-of-life tracker to look for any triggers so you can try to avoid them. Or to see if their behaviour is getting worse, so you can alert their healthcare team.

    Is your loved one behaving differently?

    BRIAN is our trusted online app where you can track your experience, compare it with others who’ve been there and get the knowledge you need to make informed decisions.

    Download our BRIAN app on the App Store    Download our BRIAN app on Google Play

    Click here to visit the BRIAN website

    What causes personality changes?

    Simpy 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. 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.

    Find out more


    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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    Coping with personality changes

    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. 

    Find out more

    Relationship Support Service

    Personality changes can place a huge amount of stress on even the healthiest relationship. In our Losing Myself report, 2 in 3 people said a brain tumour diagnosis had a negative impact on their relationship with their partner. 

    By launching our free Relationship Support Service in partnership with Relate, we hope to support couples as they manage the extra strain on a relationship that can be caused by a brain tumour diagnosis.

    I can’t recommend the Relationship Support Service highly enough to help navigate the tricky ways in which a brain tumour diagnosis can impact on a relationship.

    Read Ed's story

    Ed from Kent was diagnosed with a Grade 4 glioblastoma in June 2018 after he collapsed at work. He and his wife have recently been using the relationship service the Charity offers in partnership with Relate to help support him as a husband and father.

    My wife and I had been together for 10 years when I was diagnosed. Until then, our relationship had been so carefree. From day one, we knew that we had a long-term future together and we had a good grasp of what we both wanted that to look like too. However, my diagnosis threw all that into question overnight. We did still get married just nine months later and we soon welcomed our first child after going through IVF.

    The diagnosis really changed how I viewed myself and how I felt that other people saw me too. All of a sudden, I needed help and support to complete what should be really simple tasks. I thought that I had become a burden – someone who needed caring for – and it really knocked my confidence. This resulted in a total lack of interest in the physical side of a relationship.

    The relationship service with Relate was so empathetic. I quickly built a rapport with a professional ear which gave me the confidence to discuss in detail the emotional and practical barriers which were creating the issues in my relationship. We talked openly and real effort was made to understand my situation, offer practical solutions and also understand that sometimes maybe I didn’t want to talk.

    If someone is looking for practical or emotional relationship advice, I can’t recommend it highly enough to help navigate the tricky ways in which a brain tumour diagnosis can impact on a relationship.

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

    Find out more

    Frequently asked questions

    Will I be aware of the change to my personality?

    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.

    Will I go back to how I was before?

    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.

    Find out more

    Get support

    If you need someone to talk to or advice on where to get help, our Support and Information team is available by phone, email or live-chat.

    Share your experiences and help create change

    By taking part in our Improving Brain Tumour Care surveys and sharing your experiences, you can help us improve treatment and care for everyone affected by a brain tumour.

    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

    0808 800 0004 (free from landlines and mobiles)

    Phone lines open Mon-Fri, 09:00-17:00

    You can also join our active online community - Join our online support groups.