Printed on: February 3rd, 2026

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Menopause, HRT and cognition

Menopause, HRT and cognition  

Perimenopausal and menopausal women often describe poor concentration and ‘brain fog’ as part of their symptom package. They may worry about impending dementia, and ask whether HRT will increase or decrease their risk of Alzheimer’s disease. 

In essence:

• There is no evidence that HRT specifically treats menopausal cognitive symptoms, but it does reduce symptoms of menopause that may impact cognitive performance (e.g. night sweats and subsequent insomnia), and this may improve mental functioning and wellbeing.
• There is no evidence that HRT prevents dementia.

However, the literature looking at hormones and brain function is conflicting, and therefore confusing. In this article, we examine the evidence and see if we can make sense of it. We have primarily used an article in Post Reproductive Health to summarise the current thinking (Post Reproductive Health, 2019;25(4):200), and other papers are referenced where cited.

This article was updated in January 2026.

What is brain fog?

• Menopausal brain fog may be defined as a subjective experience of poor memory, concentration, impaired brain processing or cognitive performance.
• Around 41% of postmenopausal women complain of increased forgetfulness (compared with 31% of premenopausal women).
• Women may describe difficulties recalling names or words, maintaining a train of thought or intentions (e.g. reason for going into a room) or switching between tasks. 

What causes it?

There is some evidence that shows a role for oestrogen (or lack of) in mediating menopause-related cognitive change. Other factors may be contributory such as:

• Sleep disturbance due to vasomotor symptoms.
• Anxiety.
• Stress.
• Alcohol overuse.
• Lifestyle factors such as continual ‘multi-tasking’ and life overload! 

How bad is it? 

• Longitudinal studies suggest that verbal learning and memory (the recall of words, short stories or other verbal material) can be affected during the menopause transition, but higher-order cognitive functions (e.g. strategic thinking and planning) do not change.
• On average, cognitive performance remains within normal limits.
• Memory difficulties resolve post menopause for many women, although difficulties in verbal learning may persist. 

Is there an association with later dementia?

It is unclear whether perimenopausal brain fog is associated with development of dementia in later life. However, we can reassure women that brain fog is common in menopause and the majority of women will not develop dementia (Climacteric 2022;25 (6):570). 

While studies have shown improvement in specific areas of cognition (such as prefrontal lobe functioning and verbal or spatial working memory) with oestrogen treatment, other randomised studies assessing the overall effect of HRT on cognitive performance have not demonstrated a benefit (Neurology, 2016; 87:699; PLoS Med 2015;12: 833). 

A large UK-based cohort study from 2026 looked at the emotional and cognitive effects of menopause and HRT on 125 000 women (Psychological Medicine,2025;56 (e24):1):

• It compared three groups of women: premenopausal women (mean age 45y), postmenopausal women not on HRT (mean age 58y) and postmenopausal women on HRT (mean age 60y).  
• Menopause state was based on self-reported menstrual history.
• Cognitive testing was task based and looked at three areas: prospective memory, digit memorisation and processing speed.
• The only area in which the results for the three groups differed significantly was that postmenopausal women not on HRT had slower reaction times than premenopausal women.  

MRI imaging of a smaller cohort (10 000 participants) – of which the majority were postmenopausal women not on HRT (7500 participants) and only 760 were premenopausal women – measured the grey matter volume of areas of the brain specific to memory. It found:

• Significantly decreased grey matter volumes in postmenopausal women compared with premenopausal women.
• Volumes were also significantly lower in the HRT group compared with the non-HRT group. 

The study’s findings should be interpreted in the context that it is an observational study; this means it may be subject to confounding factors, and can only show associations rather than causation.

The British Menopause Society responded to publicity around the trial, stating “Although a reduction in grey matter was noted in menopausal women, irrespective of whether they used HRT or not, the relevance of this finding remains to be seen. Further research is needed in this area. Although there may be changes in grey matter volume in women with Alzheimer’s disease, this study is making no claims regarding a change in risk of Alzheimer’s disease with HRT, in line with four previously published randomised controlled trials.”

Importantly, MRI imaging of grey matter volume is not a diagnostic tool for cognitive impairment, and there are no standard reference ranges reflecting individual variation (Nature, 2022;604 (7906):525) 

In summary: there is no consistent evidence that HRT treats cognitive symptoms associated with menopause (although it may help indirectly by reducing vasomotor symptoms and anxiety). 

Causes of dementia

Cognitive decline can be a normal feature of getting older, but dementia is usually diagnosed when cognitive decline results in inability to function normally. There are two main pathophysiological processes:

• The accumulation of amyloid and tau proteins in the brain is a feature of Alzheimer’s dementia.
• Vascular dementia results from atherosclerotic microvascular changes. 

The development of dementia is likely to be a multifactorial process, and subtle changes may start to occur many years before the onset of symptoms. The main risk factors for dementia include being female, age, family history, head injury, smoking, obesity, diabetes, hypertension and high cholesterol. 

Premature ovarian insufficiency and cognitive decline 

Studies have shown that premature ovarian insufficiency and surgical menopause are associated with an increased risk of dementia and cognitive decline. Studies looking at the effect of HRT in this group have shown that these increased risks are mitigated by using HRT until at least the age of 50y (Climacteric, 2015; 18(4):483).

This supports the theory that oestrogen deficiency may be involved in the aetiology of cognitive decline.

Research looking at the effects of oestrogen on the human and animal brain gives a biological plausibility for a potential protective effect of HRT against dementia. 

This data has shown that oestrogen:

• Reduces deposition of amyloid in the brain.    
• Can protect brain structures related to memory such as the hippocampus and cholinergic basal forebrain.
• Improves cerebral perfusion and potentially reduces the risk of microvascular lesions. 

However, translation of these findings into significant clinical benefit of using exogenous oestrogen to reduce risk of cognitive impairment is still yet to be shown (see below).   

Studies involving women taking HRT after natural menopause have shown mixed results, as the table below highlights:

The Lancet Commission on dementia in 2024 concluded: “Overall, it is unclear whether menopause and HRT are causally related to dementia risk” (Lancet 2024;404:572).

Study designs

Different studies use different designs, populations, numbers of participants, HRT formulations and statistical analyses, and all will have some methodological flaws and confounding factors that may partially explain their conclusions. 

Past observational evidence has shown that women who use HRT have better cognitive function, although these studies may be open to bias due to confounding factors (Neuroscience,2000;101(3):485). 

More recent case–control trials (such as the large Scandinavian and UK papers published in the BMJ) suggest the opposite. But, by nature of their design, observational studies can only prove association, not causation. For example, early mild cognitive impairment in women due to dementia may be attributed to menopause, and HRT be prescribed as a result. Also, women on HRT may have more frequent interactions with healthcare professionals; therefore, any cognitive symptoms associated with dementia may be picked up earlier (BMJ,2023;381:p1404).   

Differing hormones

Oestrogen-only HRT appears, in some studies, to have a more favourable effect than combined HRT, suggesting that additional progestogen may contribute to an adverse cognitive effect. The type of both oestrogen and progestogen used may be important.   

Type of dementia

Dementia is a multifactorial disease with varying pathophysiological processes – some of which may, or may not, be impacted by hormones.

Age of woman

Most data shows an age difference in risk patterns, suggesting that oestrogen could be neuroprotective if started early in the menopause transition (as has been proposed with cardiovascular disease). A ‘healthy cell bias’ has been proposed which suggests that if neurons are healthy at time of exposure, oestrogen will have a positive effect on function; however, if neurons are already functionally compromised, the oestrogenic effect may be harmful. More research is needed to establish this ‘critical window’ hypothesis, as well as the relationship with other factors such as genetic predisposition (see below).

There are specific genotypes associated with an increased lifetime risk of Alzheimer’s disease. The APOE4 (apolipoprotein) genotype association is one of the more common and better understood.

The APOE4 genotype

• 15–25% of people carry a single copy.
• 2–3% people of European ancestry carry 2 copies (are homozygotes); they have about a 60% chance of developing Alzheimer’s by the age of 85y compared with a 10–15% chance of the background population.
• APOE4 genes seem to have greater penetration (impact) in women.

APOE4 and HRT use

The UK BIOBANK analysis study showed that cumulative lifetime exposure to oestrogen was associated with increased ‘brain ageing’ (based on the appearance of brain tissue rather than measuring cognitive impact). Subgroup analysis showed that early HRT starters had less brain ageing than late starters, but this was only apparent in APOE4 carriers (Hum Brain Mapp.2020;41(18):5141).

A subsequent UK-based observational cohort study compared the impact of HRT on the cognitive function of APOE4 carriers with non-carriers (Alzheimer’s Research and Therapy 2023;15:10). The study included 1178 women, of which 368 were APOE4 carriers. It obtained each participant’s HRT treatment data, assessed cognition using a battery of neurophysiological tests and measured medial temporal lobe volume (the ‘cognitive’ area of the brain which shrinks in Alzheimer’s). It found:

• The 31 APOE4 carriers who took HRT scored more highly in cognitive testing and had larger medial temporal lobe volumes than the 337 non-HRT users.
• Earlier initiation showed greater impact on brain volume.
• No significant impact of HRT was seen in non-APOE4 carriers.

The results show that HRT use is associated with better cognition in (a small number of) APOE4 carriers, and this benefit may be greater if HRT is introduced earlier. 

In conclusion 

This doesn’t prove that HRT prevents dementia in genetically-prone women, but it presents an interesting avenue of research, particularly if a follow-up RCT demonstrates similar benefits. We don’t currently test for APOE4 status in the NHS, although it is possible to seek testing privately in the UK (and you can buy a kit online!).

• Don’t use HRT solely to prevent dementia.

The British Menopause Society concludes that, based on current evidence, HRT:

• Is unlikely to increase the risk of dementia or have a detrimental effect on cognitive function in women initiating HRT before the age of 65y.
• Should NOT be initiated for the sole purpose of improving cognitive function or reducing the risk of dementia in postmenopausal women.
• Should NOT be used for primary or secondary prevention of dementia (Optimising the menopause transition: Joint position statement by the BMS, RCOG and SfE on best practice recommendations for the care of women experiencing the menopause).

Encourage optimal cognitive health

An International Menopause Society guidance article on decision-making and counselling menopausal women about cognition reminds us of the importance of lifestyle advice in dementia prevention:

• Around 40% of dementia is due to modifiable risk factors.
• Menopause consultation should include advice and interventions to reduce cardiovascular risk (heart health is head health!).
• We should also encourage maintenance of social engagement and connectedness (social isolation can increase risk of cognitive decline in older age).
• Remember to exercise the brain: reading, learning or developing new skills all increase cognitive reserve!  

(Climacteric 2022;25(6):570)

Menopause, HRT and cognition ‘Brain fog’ – or subjective cognitive impairment – is a common menopausal symptom, and may be partly related to other menopausal symptoms such as insomnia, vasomotor symptoms or anxiety. There is no evidence that HRT treats menopausal cognitive symptoms. Women with premature ovarian insufficiency are at increased risk of dementia, and this risk is mitigated by taking HRT until the age of natural menopause. Although some research shows that oestrogen has a positive effect on some aspects of brain function, there is no conclusive evidence that HRT prevents or causes dementia.