Thinking, memory and sex hormones

Some cancer treatments lower the amount of sex hormones in the body. These hormones are oestrogen and progesterone in women and testosterone in men.

Low levels of sex hormones can sometimes cause symptoms such as changes to memory, difficulty thinking, and problems with concentration.

It may be possible to have hormone replacement therapy (HRT) to control these symptoms. But some treatments for breast cancer aim to stop the body producing sex hormones or block their action. If you are taking these treatments, unfortunately you can’t take HRT to help control your symptoms.

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 doing more than one task at the same time.

Mild cognitive impairment or ‘chemo brain’

Doctors call these changes in memory and thought processes mild cognitive impairment (MCI). You may hear it described as ‘chemo brain’, or a general ‘fogginess’.

Women with breast cancer were the first to report these changes and they were linked to their chemotherapy. So these types of changes are commonly called chemo brain. But we don’t know whether it is the chemotherapy that causes them or not.

It doesn’t only happen after chemotherapy. It can also be a side effect of hormone treatment. For many people the changes are very subtle and get better after treatment.

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

Tips to help with changes to thinking and memory

  • 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 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

Tests for changes in thinking and memory

The only tests available are those used to test dementia. They aim to see big differences in memory and thinking. Changes after cancer treatment can be very subtle. 

A team of doctors (the International Cognition and Cancer Task Force - ICCTF) is researching new tools doctors can use to test memory changes after cancer treatment. 

Thought process changes in women

Importance of the female hormone in cognition

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

Research into natural menopause shows that memory and information processing can be affected by hormone level changes. But the research also shows that both go back to how they were once menopause is over.

It is likely that treatments that lower oestrogen levels or block oestrogen’s action may affect your ability to think, concentrate or remember things. More research is needed to find out who is most at risk of these changes.

Both chemotherapy and hormone therapies for breast cancer can affect oestrogen levels. They either stop oestrogen being made or block its action. 

Chemotherapy and thought processes

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

Hormone therapy and thought processes

There is mixed evidence on whether hormone therapies affect memory and thought processes.

Tamoxifen can affect verbal memory, such as remembering a particular word for something.

Evidence for hormone therapies called aromatase inhibitors is less clear. Some research suggests that they don’t affect cognition, but other trials have shown that they might cause mild cognitive changes.

We need more research into how hormone treatments affect cognition. 

Treatment for memory problems

Correcting hormone levels is not always possible for people with cancer. Researchers are looking into a number of treatments that may be helpful.

A trial that compared patients having hormone treatment alone with those having oestrogen added to hormone treatment suggested that patients who took only hormone therapy had reduced memory and slower thought processes.

Research is also being carried out into drugs that increase the blood and oxygen supply to brain cells.

This page is due for review. We will update this as soon as possible.

Last reviewed: 
16 Nov 2018
  • Clinical characteristics, pathophysiology, and management of non central nervous system cancer related cognitive impairment in adults
    J Wefel and others
    Cancer Journal for Clinicians, 2015. Vol 65, 123-138

  • Cognitive changes associated with ADT: a review of the Literature
    J Jamadar and others
    Asian Journal of Andrology, 2012. Vol 2, 232-238

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