Thinking and memory changes in women

Some cancer treatments lower the amount of sex hormones in the body. Low levels of sex hormones can cause problems with concentration, thinking, and memory.

What are the sex hormones?

Hormones are natural substances made by the glands of our hormone system. They are carried around our body in our bloodstream. They act as messengers to carry signals between one part of the body and another.

The main female sex hormones are oestrogen and progesterone. 

Hormone therapy to treat breast cancer can work in one of two ways:

  • lowering the levels of oestrogen
  • blocking the effect of oestrogen on cancer cells 

Thinking, memory, and cancer

Memory and the way we process information is called cognition. Cognitive ability describes how well you can remember and concentrate. This includes how you manage to do more than one task at the same time.

Mild cognitive changes or ‘chemo brain’

Cognitive changes mean changes in memory, concentration, and the way a person is able to think.

Some people notice changes in how they think and remember after hormone therapy. It may not affect you every day. You may forget a word during a sentence or struggle to remember a shopping list.

Doctors call this ‘mild cognitive impairment’. You may hear it described as ‘chemo brain’, or a general ‘fogginess’. It doesn’t only happen after chemotherapy. It can also be a side effect of hormone therapy.

We don’t know exactly what causes cognitive impairment in people with cancer. But research suggests that there might be a number of factors that contribute to it.

These include:

  • the cancer itself
  • different cancer treatments
  • low mood, stress and anxiety
  • other factors such as age

For many people, the changes are very subtle and get better after treatment. But if you have them, they can reduce your quality of life.

Researchers are still trying to find out more about how hormone treatment affects memory.

Thought process changes in women

The female hormone oestrogen plays an important part in cognition. It seems to help with remembering words, concentrating, and processing things quickly.

Research into menopause shows that memory and information processing can be affected by changes in hormone levels.

It is likely that treatments that lower oestrogen levels or block the action of oestrogen may affect your ability to think. They may also affect your concentration and ability to remember things. More research is needed to find out who is most at risk of these changes.  

Both chemotherapy and hormone therapy for breast cancer can affect oestrogen levels.

Chemotherapy and thought processes

Some chemotherapy drugs can stop the ovaries making oestrogen. This may explain changes in memory and thought processes. Depending on your age, the changes may be temporary or permanent.

Hormone therapy and thought processes

Some studies show that hormone therapies such as tamoxifen and aromatase inhibitors can affect memory. For example, remembering a particular word for something. But we need more research to understand exactly how hormone therapy affects memory and thinking.

Tips to help with changes to thinking and memory

There are things that you can do that may help you cope better with these changes: 

  • Keep a diary or calendar to help you remember what you need to do each day.
  • Write lists of jobs to do, things to buy or where you keep things you use every day.
  • Use post-it notes to remind you to do tasks.
  • Write down people's names with a description to remember them.
  • Repeat information back to people to check understanding.
  • Keep your mind active, you could try crosswords, sudoku or puzzles.
  • Avoid trying to do too many things at the same time.
  • Aim to get a good night's sleep and rest in the day when you need to. Try to avoid becoming overtired.
  • Try to exercise each day if possible, this can help you to sleep and lift your mood.

Hormone replacement therapy (HRT)

One way to help control hormonal symptoms is to take hormones to replace the ones your body is no longer producing. Hormone replacement therapy (HRT) Open a glossary item is an effective treatment for many women. But some treatments for breast cancer aim to either stop the body producing sex hormones, or block their action. If you are having these treatments, you can’t unfortunately take HRT.

Doctors don’t routinely recommend that you take HRT if you have a hormone dependent Open a glossary item cancer, such as breast cancer. Even if you have finished treatment there is concern that HRT may increase the risk of cancer coming back. Talk to your specialist if you are finding it difficult to cope with your symptoms. They can explain the risks and benefits of HRT and if this is an option for you.


Researchers think that cancer treatment might make cognitive changes worse. Particularly in people who already have mild changes before treatment. They are doing tests, for example, memory tests, before starting treatment and afterwards to find out more.


There are things you can do to help you cope and improve your symptoms.

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    L Haggstrom and others

    Cancers, 2022. Volume 14, Issue 4, Page 920.

  • Menopause and cognitive impairment: A narrative review of current knowledge
    D M Conde and others
    World Journal of Psychiatry, 2021. Volume 11, Issue 8, Pages 412–428.

  • Effects of tamoxifen on cognition and language in women with breast cancer: A systematic search and a scoping review

    F Jebahi and others

    Psycho-Oncology, 2021. Volume 30, Issue 8, Pages 1262-1277

  • Oestrogen Effects on Cognitive and Synaptic Health Over the Lifecourse

    Y Hara and others

    Physiological Reviews, 2015. Volume 95, Issue 3, Page 785–807.

  • The Menopause Transition: Signs, Symptoms, and Management Options

    N Santoro and others

    The Journal of Clinical Endocrinology & Metabolism, 2021. Volume 106, Issue 1, Pages 1–15

Last reviewed: 
14 Oct 2022
Next review due: 
14 Oct 2025

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