The guide / Part 17

Perimenopause and memory: what the research says

By The Prolongeva Editorial Team Written from the published research cited in each article Updated October 2026

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You walk into a room and the reason is gone. You lose a word mid-sentence, or feel your thinking has slowed, around the same time your periods change. Many people wonder whether the two are connected. This guide sticks to the studies and official pages we opened, and says where they stop.

What do people report during perimenopause?

The NHS lists problems with memory or concentration among the symptoms of perimenopause and menopause, alongside mood swings, low mood and depression. It says brain fog may feel worse if you have sleep problems.

The NHS adds that perimenopause and menopause are different for everyone: some people have symptoms with a big impact on daily life, and others hardly have any. It says menopause usually affects women between 45 and 55 but can happen earlier, and that symptoms usually last 7 to 9 years, sometimes longer, and can change over that time.

The SWAN fact sheet says about two-thirds of women reported memory complaints such as forgetfulness during the menopause transition. That is a report of what women notice, not a test result. The studies we read describe women. Anyone who goes through this transition, however they identify, may find the questions relevant, though we found no data here on other groups.

What did the SWAN study actually measure?

SWAN is the Study of Women's Health Across the Nation, a US cohort that followed women through the menopause transition. In the 2009 analysis (Greendale et al., Neurology), 2,362 participants were followed for 4 years and tested on three things: processing speed, verbal memory and working memory.

The finding is easy to misread, so here it is plainly. The key result was about learning from repetition. Women tested before menopause, in early perimenopause and after menopause scored higher the more often they took the speed test. Women in late perimenopause did not improve over time. On delayed verbal recall, scores climbed in premenopause and postmenopause but not during early or late perimenopause.

Two cautions. The authors say "may be time-limited", which is a suggestion, not a promise. And a group average does not tell you what is happening for you. The SWAN fact sheet adds that after menopause, processing speed fell, while declines in verbal and working memory typically did not start until after ages 58 and 61.

Do sleep, mood and hot flashes explain it?

A 2010 SWAN analysis (Greendale et al., American Journal of Epidemiology; 1,903 midlife women followed 6 years) tested exactly this. Depressive symptoms were linked to a small drop in processing speed. Earlier high anxiety was linked to a smaller learning rate on verbal memory. Self-reported sleep disturbance and hot flashes were not related to cognitive performance there.

Importantly, the abstract says these symptom groups did not account for the transient decrement in learning on the speed test (SDMT) seen during late perimenopause. The authors listed limits, including a small test battery with ceiling effects, symptoms recalled over only 2 weeks, and no measure of how bothersome they were.

That does not mean sleep or hot flashes never matter. The SWAN fact sheet notes that in early postmenopause, women with more wakefulness and fragmented sleep scored lower on processing speed, and that other studies found objectively measured hot flashes associated with memory difficulties. In our reading, the evidence is mixed. We cover the sleep side in sleep and memory after 45 and the mood side in stress and memory.

What can hormone therapy do, and not do, for memory?

We are not recommending or discouraging it; that is a decision for you and a clinician. Here is what the sources we read say.

• The 2009 SWAN study was observational. Hormone initiation before the final menstrual period was linked to a beneficial effect and initiation after it to a detrimental effect, and current hormone users after menopause scored lower than premenopausal women. Observational data cannot show cause, since women who use hormones differ from those who do not.
• The 2022 NAMS position statement says three large randomized trials showed neutral effects on cognition when hormone therapy was used early in the postmenopause period. It also says estrogen therapy may have cognitive benefits when started right after surgical removal of the uterus and both ovaries, based on small trials.
• Women over 65: in the WHI Memory Study, estrogen plus progestin started after 65 was linked to doubled dementia risk (23 cases per 10,000 person-years, per the 2022 NAMS statement citing the WHI Memory Study).

The same statement says hormone therapy remains the most effective treatment for hot flashes and night sweats (vasomotor symptoms), with the balance of benefit and risk depending on age, time since menopause and personal history. That is about those symptoms, not memory. We found no guideline here that recommends it for memory alone, and a doctor can weigh your history.

What else can look like perimenopause brain fog?

Quite a bit. The NHS lists tiredness, difficulty concentrating or thinking clearly, and low mood or depression among symptoms of an underactive thyroid, and says some of these symptoms are common and can have other causes, so they are worth getting checked. It says blood tests measure thyroid-stimulating hormone and thyroxine. See thyroid and brain fog.

The NHS memory loss page names stress, anxiety or depression, and sleeping problems (insomnia) as causes of memory loss, and says not to try to self-diagnose. Medicines are another possibility. We did not open a source on specific drugs, so ask a pharmacist or clinician to review what you take.

In practice, several of these can sit on top of each other with the transition, which is why guessing is hard from the inside. Our overview of brain fog in the 40s and 50s covers the wider picture.

When is it worth talking to a doctor?

The NHS says to see a GP if you think you have symptoms of perimenopause or menopause and want to know your options, or if memory problems are affecting your day-to-day life. The SWAN fact sheet says memory changes that come on suddenly should be reported to your primary health care provider.

• Memory or thinking changes that are getting worse, or that someone close to you has noticed.
• Low mood, anxiety or poor sleep that is hard to shake.
• Symptoms such as a fast heartbeat (palpitations), which the NHS also lists as a reason to call.
• You take medicines and have noticed a change since starting one.

A visit can cover your cycle, sleep, mood, thyroid and medicines together. Our questions to ask your doctor about memory can help you prepare, and normal aging vs. early dementia explains how clinicians think about the difference.

This article is general information, not medical advice. If memory or thinking changes are worrying you, please talk to a doctor or pharmacist.