PERIMENOPAUSE AND BRAIN FOG
Why you can't find your words and what actually helps.
By Katie Rice | Accredited Naturopath & Nutritionist | Her Herbs Founder
You walk into a room and forget why. You're mid-sentence and the word just isn't there. You reread the same paragraph three times and none of it lands. You've started wondering, quietly, whether something is actually wrong with your brain.
It probably isn't. But I understand why it feels that way, and I want to walk you through what's actually happening.
Brain Fog Is Real, Even When the Tests Look Normal
This is one of the more reassuring and more frustrating pieces of the research at the same time.
A 2026 study found that perimenopausal women were significantly more likely to report cognitive symptoms like forgetfulness and trouble concentrating, but when their actual cognitive performance was tested, the objective changes were minimal. A separate 2026 report from King's College London found no evidence that perimenopause produces a lasting impact on overall cognitive performance, despite self-reported brain fog being clearly elevated.
What this tells us is important. Your experience is genuine. The forgetfulness, the word-finding difficulty, the mental fatigue, these are real and they are common. But the underlying cognitive decline that the word "fog" might suggest usually isn't happening in any measurable way. For the large majority of women, this is not early dementia and it is not a sign of permanent decline.
It's a symptom. A disruptive, frustrating, very real symptom. Just not a diagnosis of something worse.
Why It Happens
Oestrogen plays a genuine role in cognitive function. It interacts with serotonin, acetylcholine, and other neurotransmitter systems involved in memory, attention, and mental flexibility. As oestrogen fluctuates during perimenopause, those systems are affected, which is part of why concentration and recall can feel less reliable than they used to.
But the research increasingly frames brain fog as a whole-body symptom rather than a direct, isolated hormonal effect. Insomnia, hot flushes, anxiety, stress load, and even cardiovascular factors all contribute to how clearly you think. In practice, this means brain fog is often the downstream result of poor sleep and a taxed nervous system as much as it is a direct hormonal effect on the brain itself.
If you've also been dealing with disrupted sleep, anxiety, or fatigue during this transition, and most women going through perimenopause have, your brain fog is very likely connected to all of it, not operating in isolation.
The Highest-Yield Places to Start
If the goal is to actually reduce brain fog, the research points toward a clear order of priority.
Fix sleep first. This is consistently identified as the single biggest lever. Poor sleep directly impairs concentration, memory consolidation, and word-finding, independent of any hormonal change. If your sleep has been disrupted, addressing that is very likely to be the single most effective thing you can do for your mental clarity. I've written about this in more detail in the Her Herbs piece on perimenopause and sleep, because the two are so closely linked.
Stabilise blood sugar. Energy availability to the brain depends on stable glucose. Skipping meals, relying on caffeine, or eating in a way that causes blood sugar swings will worsen concentration and mental fatigue regardless of what your hormones are doing. Regular meals built around protein, fibre, and healthy fats support more consistent mental energy throughout the day.
Move your body. Regular exercise, ideally a mix of aerobic and resistance training, improves circulation, insulin sensitivity, mood, and cognition. This isn't just a general health recommendation. It has a specific, evidence-backed effect on cognitive symptoms during perimenopause.
Manage stress and vasomotor symptoms. Hot flushes, night sweats, and anxiety all add to what researchers describe as cognitive load, essentially the mental bandwidth your brain has available. Reducing that load, whether through addressing hot flushes directly or through nervous system support like mindfulness or yoga, frees up cognitive resources that are otherwise being used to manage physical and emotional stress.
Nutrients and Food
A Mediterranean style eating pattern comes up consistently in the research for supporting both cardiometabolic and brain health. Vegetables, fruit, legumes, nuts, seeds, olive oil, and fish form the foundation, and this pattern is well supported for cognition specifically, not just general wellbeing.
Magnesium, omega-3 fatty acids, B vitamins, and adequate protein are the nutrients most commonly associated with supporting neurotransmitter production and energy metabolism during this transition. The evidence here is more modest than for sleep and exercise, but these nutrients work best when they're correcting an actual gap, which is common during a period of increased physiological demand like perimenopause.
Hydration matters more than people expect. Even mild dehydration measurably affects concentration, and it's an easy thing to overlook during a busy day.
Herbal Support
A number of herbs are used in naturopathic practice to support the nervous system and hormonal balance during perimenopause, and some have a longer history of use for cognitive and mood symptoms specifically than others. What's appropriate depends on your individual symptom picture, any medications you're taking, and your broader health history. This is genuinely an area where individualised guidance matters, because the wrong herb for your situation can be ineffective at best and interact with other treatments at worst. Working with a naturopath to identify the right support for you, rather than self-selecting from a list, is where this approach is most useful.
When to Look Further
Most brain fog in perimenopause is uncomfortable but not a sign of anything more serious. That said, it's worth taking more seriously and investigating further if it comes on suddenly, is severe, or is accompanied by significant mood change, headaches, neurological symptoms, heavy bleeding, signs of thyroid dysfunction, or profound fatigue that doesn't improve.
Those signs warrant ruling out anaemia, thyroid disease, depression, sleep apnoea, or medication side effects. Perimenopause can absolutely be part of the picture, but it shouldn't be treated as the automatic explanation for everything. If something feels disproportionate or doesn't fit the pattern, it's always worth raising with your GP.
If you want to go deeper on naturopathic support through the perimenopause transition, the Her Herbs Perimenopause Series covers the full picture.
EXPLORE THE HER HERBS PERIMENOPAUSE SERIES
A Note From Katie
"Brain fog was one of the symptoms women apologised for the most in clinic. They'd lose a word mid-sentence and laugh it off, embarrassed, worried it meant something was wrong. I want to say clearly what I told them. This is a real, common, and usually temporary symptom of a significant hormonal transition. It is not a sign that your mind is failing you. Once we addressed sleep, blood sugar, and nervous system load, most women found real improvement. You are not losing yourself. You're moving through something, and there is support for it."
-Katie Rice, Naturopath & Founder, Her Herbs
This content is for educational purposes only and does not constitute medical advice. Please consult your healthcare provider regarding your individual health concerns.
