Perimenopause brain fog: is it hormones or something else?

Yes, brain fog is a common part of perimenopause. The NHS lists problems with memory and concentration among its symptoms [1], and a large US study found that the usual gains on repeated memory and thinking tests stalled during perimenopause and came back after menopause [2]. Brain fog is usually subtle on tests even when it feels big, but new or worsening memory problems are always worth checking with your doctor.

“I stood in the middle of a meeting and the word was just gone.” I hear sentences like that often, usually from women in their mid-40s who are used to keeping many things in their heads at once. Many of them quietly wonder if it’s the start of something worse. Below I go through what research says, how brain fog differs from dementia, what else can sit behind it and how we can work with it.

What does perimenopause brain fog feel like?

Brain fog isn’t a recognized clinical syndrome [4]. Researchers use the word for the thinking and memory problems that many women notice around menopause [4]. The ones I hear about most:

• losing a word or a name mid-sentence
• walking into a room and forgetting why
• reading the same paragraph three times
• finding it harder to focus, or to switch between tasks
• feeling slower than you used to

The NHS groups poor memory and brain fog with mood changes, and notes that memory and concentration problems may feel worse when you’re also short on sleep and tired [1].

What research says about memory in perimenopause

The best-known data come from SWAN, the Study of Women’s Health Across the Nation. Researchers tested 2,362 women each year for four years. Normally, people get a little better each time they take the same tests, because they learn them. On a test of processing speed, that happened in premenopause, early perimenopause and postmenopause, but not in late perimenopause. On verbal memory tests, scores improved in premenopause and postmenopause, but not in early or late perimenopause [2]. The authors describe the difficulties as subtle, a lack of improvement rather than a drop in scores, and temporary [2].

Not every study points the same way. A 2013 meta-analysis found that postmenopausal women scored slightly lower than premenopausal women on delayed verbal memory, while perimenopausal women didn’t differ significantly from premenopausal women. The authors describe the effects as small [3].

There is also a gap between how brain fog feels and what tests show. A 2025 systematic review found that how women rated their own memory and thinking had little connection with their test results overall. The one link they found, a small one, was with learning efficiency [4]. In other words, what you notice in daily life is real, and standard tests may simply not capture it well. The authors note that there is still no validated way to measure menopausal brain fog [4].

Brain fog or dementia?

This is the question many women don’t say out loud. Here is what helps to know.

Dementia is not a natural part of aging [5]. Early signs the NHS lists include memory loss, difficulty concentrating, trouble with familiar daily tasks, struggling to follow a conversation or find the right word, confusion about time and place, and mood changes [5]. Some of these overlap with brain fog, which is exactly why it’s hard to judge on your own.

A few things the NHS describes as typical early signs of Alzheimer’s disease are regularly forgetting recent events, names and faces, and asking the same questions again and again [5]. It also notes that people don’t always notice their own symptoms, and that family and friends may notice first [5].

In SWAN, the dip in learning was tied to perimenopause and eased afterward [2]. Researchers are still working on ways to tell menopause-related memory concerns apart from early dementia, which is one reason a proper assessment matters if you’re worried [4]. That assessment is done by your doctor, and the NHS advice is to talk to a doctor sooner rather than later if you’re worried about your memory [5].

What else can affect memory and focus?

Perimenopause rarely comes alone. A few things that often travel with it:

• Sleep. Night sweats and early waking leave less rest, and the NHS notes this can make memory problems feel worse [1]. More in perimenopause insomnia.
• Mood. In SWAN, more depressive symptoms were linked with slower processing speed, and more anxiety with less learning on memory tests [2]. The 2013 meta-analysis also found higher odds of depressive symptoms in perimenopause [3].
• Thyroid. An underactive thyroid can cause difficulty concentrating or thinking clearly, tiredness, low mood and irregular or heavy periods [6]. Much of that overlaps with perimenopause.

That’s why I find it useful to look at the whole picture, instead of putting every symptom down to hormones. You can read about the wider range of signs in perimenopause symptoms.

Small things that make daily life easier

These don’t change your hormones, but many women find they take some pressure off:

• write things down, and keep one list instead of five
• do the demanding tasks at the time of day you think most clearly
• do one thing at a time where you can
• protect your sleep where possible, even if nights are broken
• keep a short diary for 4 to 6 weeks: sleep, cycle, mood and the days your memory feels worst

The diary also gives you something concrete to bring to your vårdcentral (local primary care clinic) or gynecologist.

How I work with brain fog in perimenopause

At your first visit, we go through your whole story: sleep, cycle, stress, food, digestion and what you’ve already tried. The visit is 60 minutes, at Kommendörsgatan in Östermalm or online, in English or Swedish.

After the visit, you get a written plan. It can include advice on food, sleep and stress, Chinese and Western herbs, supplements and acupuncture, mainly Japanese style. I often look at nutrient deficiencies and anemia, which can add to tiredness. If it makes sense, we add lab tests, functional testing alongside conventional tests, as a basis for your plan and for your conversations with your doctor.

I work in parallel with your doctor, whether or not you take HRT. If you’re unsure whether your situation fits, you can book a free 15-minute call on Tuesdays, or send me an email first. You’ll find more on my perimenopause page, and all options on prices.

When to see a doctor

Contact your vårdcentral or 1177 (Sweden’s public health information service) if:

• your memory problems are getting worse, or you’re worried about them [5]
• you regularly forget recent events, names and faces, or repeat the same questions [5]
• you get confused about time and place, or struggle with familiar tasks [5]
• people close to you have started to notice changes in your memory [5]
• you also have new, severe or unclear symptoms, or low mood that doesn’t lift

Call 112 right away if confusion, memory loss or trouble speaking come on suddenly, or if one side of the face droops, or one arm or side of the body goes weak or numb. These can be signs of a stroke. Get help even if the symptoms pass [7].

Sources

1. NHS. Symptoms of menopause and perimenopause. https://www.nhs.uk/conditions/menopause/symptoms/
2. Greendale GA, Derby CA, Maki PM. Perimenopause and cognition. Obstetrics and Gynecology Clinics of North America, 2011. https://pmc.ncbi.nlm.nih.gov/articles/PMC3185244/
3. Weber MT, Maki PM, McDermott MP. Cognition and mood in perimenopause: a systematic review and meta-analysis. Journal of Steroid Biochemistry and Molecular Biology, 2013. https://pmc.ncbi.nlm.nih.gov/articles/PMC3830624/
4. Furey RT, Thomas EHX, Kulkarni J, Gurvich C. Subjective versus objective cognition during menopause: a systematic review and meta-analysis. Journal of the International Neuropsychological Society, 2025. https://www.cambridge.org/core/product/E9889C5BBD621547C0EB25996EBDAFBD
5. NHS. Symptoms of dementia. https://www.nhs.uk/conditions/dementia/symptoms-and-diagnosis/symptoms/
6. NHS. Underactive thyroid (hypothyroidism): symptoms. https://www.nhs.uk/conditions/underactive-thyroid-hypothyroidism/symptoms/
7. NHS. Stroke: symptoms. https://www.nhs.uk/conditions/stroke/symptoms/