• Brain fog is moments of forgetfulness or wooliness
• Decreasing hormone levels have an impact on brain function
• Changes are usually temporary and can be improved by replacing missing hormones and lifestyle changes
Brain fog isn’t a medical term, but it describes those moments of forgetfulness, confusion or ‘woolliness’, where you just can’t think straight. It can present itself in numerous ways, including struggling to find a simple word, forgetting things, reading the same page of a book over and over because you can’t take in the information, or not being able to maintain a train of thought.
Your brain can feel sluggish when you’re jetlagged, hungover, or poorly with a cold or flu. Some people experienced it as a symptom of COVID. However, brain fog is also a common symptom of changing or low hormone levels in your brain, especially testosterone.
RELATED: Hormones and brain health
Your brain produces progesterone, estradiol and testosterone and these hormones are involved in important processes in your brain. When they bind to the receptors in your brain, they activate a cascade of molecular events, including activating your immune system, reducing inflammation, increasing levels of other neurotransmitters such as serotonin, dopamine and melatonin, burning glucose faster to make more energy, and increasing blood flow to your brain. These actions are neuroprotective.
More specifically, estradiol increases the number of connections in your hippocampus [1], the part of your brain important for memory and certain types of learning.
Progesterone has an important role in cognition, regulating mood, inflammation and repair and function of cells, including nerve cells.
Testosterone strengthens nerves in your brain and contributes to mental sharpness and clarity [2]; it also strengthens arteries that supply blood flow to your brain, which may be crucial in protecting against memory loss.
Levels of testosterone often reduce when women are in their late 20s and early 30s. This means that you can have low testosterone when your levels of estradiol (a type of estrogen) and progesterone are normal.
RELATED: Testosterone revisited
When hormone levels fluctuate and reduce, women can experience difficulty recalling words and numbers, misplacing items, trouble concentrating (absent mindedness, losing a train of thought, more easily distracted) and forgetting appointments and events.
Cognitive issues can be frustrating and worrying, and for some women, they can be debilitating. Symptoms of perimenopause and menopause can lead to reduced cognitive functioning which can persist. These symptoms can lead to social anxiety and withdrawal from daily life.
RELATED: Driving anxiety and menopause
Women all over the world use the Balance app to log their symptoms and brain fog has been revealed as the most common symptom – 446,147 women have logged it [3]. Similarly, 1,352 new patients at Newson Clinic completed a symptom questionnaire – memory problems were reported by 94% of women, making it the second most common symptoms (after fatigue or low energy) [4]. Difficulty in concentrating was reported by 92% of women and word-finding difficulty was reported by 90%.
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Low hormones during perimenopause and menopause can increase future risk of dementia. Studies have shown for many years that women have an increased risk of dementia when they are menopausal, and this risk increases the longer a woman is without hormones.
Women who have had a bilateral oophorectomy (surgery to remove both ovaries) have an increased risk of cognitive decline and dementia, with studies suggesting a significant neuroprotective effect of estrogen naturally produced by the ovaries before age 50 years [5]. Women who experience premature or early menopause should consider being prescribed replacement hormones [5].
RELATED: Brain fog or dementia?
There is no single test that can diagnose brain fog. It’s important you speak to a healthcare professional about any concerns you have as they will be able to help determine what steps you can take.
Taking the right dose and type of hormones – progesterone, estradiol and testosterone – can really improve memory and reduce brain fog.
If you suspect your testosterone levels are low, you can have a blood test to measure testosterone and sex hormone binding globulin (SHBG) – this will allow your clinician to work out the free androgen index (FAI), which is the amount of active testosterone that’s available to your body. If you decide to take replacement testosterone, your levels will be monitored to assess your response to treatment and to ensure they remain within the normal female range.
Researchers have closely studied how testosterone levels affect men, especially in areas like memory, recall of information and decision making with promising results reported after testosterone supplementation [6].
Newson Clinic carried out an audit of its perimenopausal and menopausal patients - women who were already taking HRT (estradiol and/or progesterone). They completed a questionnaire measuring their symptoms before and after testosterone was added to their regimen. Before taking testosterone, memory problems were reported by 91% of the women and the audit found testosterone significantly improved concentration and memory - 39% of women reported an improvement in cognition [7].
These results align with those of previous studies that have demonstrated improvements in cognition in women treated with testosterone therapy. For instance, one randomised control trial found transdermal testosterone treatment resulted in a better performance in a task that tested verbal learning and memory in women [8].
RELATED: Can HRT reduce your risk of dementia?
Brain fog may improve with changes to your lifestyle but if it is due to low hormones, especially testosterone then it will not improve without replacing the missing hormones.
Regular exercise can boost memory and improve your mood and sleep. Your brain needs good quality sleep so that it can process, repair and improve memory retention. A calming bedtime routine can be beneficial, and some women find taking a magnesium supplement helpful.
Dietary changes can boost memory – ensure you are getting the right balance of vitamins and limit highly processed foods and those high in saturated fats. There is some evidence that eating a Mediterranean-style diet can reduce the risk of mild cognitive impairment and Alzheimer’s disease [9].
RELATED: Can the Mediterranean diet help menopausal symptoms?
Vitamin D is essential for healthy brain function and low levels of vitamin D have been linked to poor cognition in some people [10]. Dietary sources don’t generally provide adequate amounts of vitamin D and in the UK and many other countries it can be difficult to achieve adequate vitamin D levels through sun exposure. This makes supplementation a beneficial option.
RELATED: All about vitamin D, menopause and hormone health
If you find your memory lapses embarrassing, don’t be tempted to avoid company – socialising can stimulate your memory. It can also help to treat your brain like a muscle – it needs exercise to keep it functioning at its best. Mentally stimulating activities, such as playing board games, crafts, reading, word and number games, learning a language, can help.
Planning ahead can help with the anxiety that can arise from brain fog. Keep a diary and within it schedule preparation time for any tasks that need doing, plus breathing space in between appointments so you get a chance to refocus and prepare. Remember to be patient with your brain and practice self-compassion.
RELATED: The menopause brain: why it might be feeling strange and what you can do about it
Finally, if you feel your brain fog and memory problems could be related to your hormones, especially testosterone, then you should speak to a healthcare professional who understands hormones.
Too often women are incorrectly told that low testosterone is only related to libido but this is not current.
1. Luine V., Frankfurt M. (2013), ‘Interactions between estradiol, BDNF and dendritic spines in promoting memory’, Neuroscience, 3 239, pp.34-45. https://doi.org/10.1016/j.neuroscience.2012.10.019
2. Celec P., Ostatníková D., Hodosy, J. (2015), ‘On the effects of testosterone on brain behavioral functions’, Frontiers of Neuroscience. 17;9:12. doi: 10.3389/fnins.2015.00012
3. Balance report to October 2025
4. New patients attending Newson Clinic, March-June 2025
5. Rocca W.A., Grossardt B.R., Shuster L.T. (2014), ‘Oophorectomy, estrogen, and dementia: A 2014 update’, Molecular and Cellular Endocrinology, 389(1–2) pp7-12, https://doi.org/10.1016/j.mce.2014.01.020
6. Hua JT, Hildreth KL, Pelak VS. (2016), ‘Effects of Testosterone Therapy on Cognitive Function in Aging: A Systematic Review’, Cogn Behav Neurol. 29(3):122-38. doi: 10.1097/WNN.0000000000000104
7. Glynne S., Kamal A., Kamel A.M. et al. (2025), ‘Effect of transdermal testosterone therapy on mood and cognitive symptoms in peri- and postmenopausal women: a pilot study’, Arch Womens Ment Health, 28, pp541–550. https://doi.org/10.1007/s00737-024-01513-6
8. Davis S.R., Jane F, Robinson P.J., Davison S.L., Worsley R., Maruff P., Bell R.J. (2014), ‘Transdermal testosterone improves verbal learning and memory in postmenopausal women not on oestrogen therapy’, Clin Endocrinol (Oxf), 81(4) pp621-8. Doi: 10.1111/cen.12459
9. Fu J., Tan L-J., Lee J.E. and Shin S. (2022), ‘Association between the mediterranean diet and cognitive health among healthy adults: A systematic review and meta-analysis’, Front. Nutr. 9:946361. Doi: 10.3389/fnut.2022.946361
10. Goodwill A.M., Szoeke C. (2017), ‘A Systematic Review and Meta-Analysis of The Effect of Low Vitamin D on Cognition’, J Am Geriatr Soc, 65(10) pp2161-2168. Doi: 10.1111/jgs.15012
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