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Personality changes and brain tumours

Our brains control every aspect of who we are, what we think and feel. Brain tumours can sometimes cause personality changes such as confusion, anxiety or mood swings.

This happens most often when the tumour is in the frontal lobe of the brain but can occur with any brain tumour and can also be due to the impact of diagnosis and treatment. The effects may be temporary or permanent and there are many strategies to help cope with personality changes

What sort of personality changes can brain tumour cause?

If you have or had a brain tumour, you may experience changes to aspects of your personality. Personality changes may include:

Read more about other brain tumour side effects.

Why can brain tumours cause personality changes?

There could be several reasons why you or your loved one may experience personality changes, each of which could be interlinked. Knowing that there is a reason for the personality change can feel hugely relieving and can make a big difference in starting to cope emotionally.

Location of the tumour

As a brain tumour grows, it puts pressure on surrounding tissue affecting the function, process or part of the body that is controlled by that area of the brain. Personality changes are most common in people when the tumour is located in their frontal lobe. This is because the frontal lobe is responsible for many functions - it controls your personality and emotions and plays a vital role in problem solving and long-term memory.

Our ability to regulate our behaviour and restrain ourselves is also controlled in the frontal lobe so, if you have a tumour here, you may act in ways that are considered socially inappropriate. This can be very difficult for those around you to understand and can put a strain on personal relationships.

As well as the frontal lobe, personality changes can be caused by a tumour in the pituitary gland. The pituitary gland is not technically part of the brain, but it is located very near to the brainstem.

The pituitary gland secretes hormones, so a tumour here can lead to the over or under production of hormones, affecting some emotions and causing changes in your sex drive. Treatments such as hormone replacement therapy can help to redress this balance, if appropriate.


Another possible reason for personality change is swelling in the brain (known as 'oedema'). This could result from treatments including surgery, radiotherapy and chemotherapy. Personality changes that have occurred as a direct or indirect result of these treatments usually pass gradually as you recover from the treatment.

Large tumours can have a greater effect on personality as they affect a greater area. However, even a small tumour in a key structure of the brain can have a significant impact. A lower grade (1 or 2), slow growing tumour often allows the brain more time to adapt around it, causing less swelling and personality change than a higher grade (3 or 4) tumour, which grows more quickly.

Steroids help to reduce swelling and therefore reduces personality effects, although they can also affect your emotions; you may feel anxious, irritable and emotional and experience mood swings. A small number of people may experience what is referred to as 'steroid' induced psychosis

The impact of the diagnosis and treatment

Personality changes might be experienced as a natural reaction to the diagnosis and treatment. The emotional impact of the diagnosis, undergoing treatment, and the lifestyle changes that are often necessary for a person living with a brain tumour, can affect mood, general persona and can cause a person to become more irritable.

Treatment and frequent journeys to medical appointments, can also dramatically lower energy levels, so someone who was very active before they had a brain tumour may no longer be. Confusion and mood swings can also be the result of medication or combination of medications interacting. It is worth speaking to your doctor if you are experiencing such effects as they may be able to alter your medication.

Frequently asked questions

Will I be aware of the change to my personality?

This varies. Some people are aware of their personality changes, some people aren't, or they may not have full awareness. For example someone may be aware that they are less patient and have a shorter temper than they did before 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.

Discovering the source of the problem is the first step and a way to evaluate changes in personality is to consult with a neuropsychologist. Neuropsychologists specialise in physical effects of brain disease or injury on mental abilities.

In a neuropsychological assessment, the neuropsychologist conducts a series of tests examining memory, thinking speed, attention, concentration, language, motor skills and mood. They also assess the executive functions which include planning and organising. Information is often collected from friends and families as you may be unaware of the changes to your personality.

The results of the tests help the neuropsychologist decide if there is any need for therapies, medications or strategies to help make adaptions.

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 extent of personality change will really depend on what is causing it and which area of the brain is affected. Personality changes may be helped by medication or they may fade with time as the effects of treatment have worn off.

If the change is due to the emotional impact of living with a brain tumour, psychological support can help.

If the change is physical in the brain, for example, it is the result of surgery or radiotherapy, the person may not go back to the way they were before. 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.

Relationship Support

We know that a brain tumour diagnosis often impacts the wider family. In our 'Losing Myself' report, 2 in 3 said that they had seen a negative impact on their relationship with their partner, while 72% have had physical intimacy affected. Studies show that it is the personality and cognitive effects of brain tumours that place the most strain on relationships, particularly where they cause behaviour change, but that techniques to support caregivers can make a positive difference.


Click is an online resource that's been developed by OnePlusOne to provide general relationship support and help you strengthen your relationships. It features a professional-led listening room, moderated community posts, evidence-based articles, goal-setting, quizzes, and personalised recommendations to help you improve and maintain the quality of your relationships.

Relate are a charity who provide support services to people experiencing relationship problems, this includes counselling for individuals, couples and families.

You can visit the British Association for Counselling and Psychotherapy (BACP) for information about finding a therapist.

The British Psychological Society (BPS) has information about finding a chartered psychologist.

The Brain Tumour Charity are currently undertaking research into how best to support people living with a brain tumour who are affected by personality changes. If you would like to know more, please contact the support team at or call 0808 800 0004.

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.

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:

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