Why You Can't Remember Words Anymore (And What It Really Means)
You're in the middle of a sentence and the word just... vanishes. You know what you want to say. You can picture the concept. But the actual word? Gone.
Or you walk into a room and completely forget why you went there. You lose your train of thought mid-meeting. You read the same paragraph three times and still can't remember what it said. You forget names of people you've known for years.
And the terrifying thought creeps in: Is this early onset dementia? Am I losing my mind?
Let me give you the short answer: No. This is not dementia. This is your hormones, your stress response, and your metabolic function affecting your brain - and it's reversible.
The Brain Fog That Nobody Warned You About
One of the things I hear over and over again - especially from professional women - is how derailing brain fog is for them. More than weight gain, more than fatigue, the cognitive changes feel like they’re losing a fundamental part of who they are.
They've always been sharp. Quick-thinking. On top of things. Building careers on their ability to manage complex problems, remember details, make decisions quickly. Their brain was reliable.
And now? They're forgetting appointments. Missing deadlines because they genuinely forgot about them. Struggling to follow conversations. Taking twice as long to complete tasks that used to be automatic.
This isn't just aging. This is specific, measurable changes in brain function caused by hormonal and metabolic shifts - changes that show up in your 40s for very specific reasons.
What's Actually Happening in Your Brain
Your brain is incredibly sensitive to hormone levels. When oestrogen, progesterone, cortisol, and thyroid hormones shift - as they do dramatically in your 40s - your brain function shifts with them:
Oestrogen affects:
Memory and recall (especially verbal memory)
Neurotransmitter production (serotonin, dopamine)
Blood flow to the brain
How your brain cells communicate with each other
When oestrogen fluctuates or declines, all of the above can become less efficient. That word you can't remember? That's not random - it's related to how oestrogen affects the hippocampus and prefrontal cortex.
Progesterone affects:
Anxiety and mental clarity
How well you handle stress
GABA production (your brain's calming neurotransmitter)
Sleep quality (your brain needs deep sleep to consolidate memories)
When progesterone drops, your brain becomes more reactive to stress, your sleep quality suffers, and your ability to think clearly under pressure diminishes.
Cortisol affects:
Your hippocampus (the brain's memory center)
Prefrontal cortex function (decision-making, focus, working memory)
Neuroplasticity (your brain's ability to form new connections)
Neurotransmitter balance
Chronic stress and elevated cortisol literally shrink your hippocampus and impair prefrontal cortex function.
Thyroid hormones affect:
Brain metabolism and energy production
Neurotransmitter synthesis
Myelin production (the insulation around neurons)
Overall processing speed
Even subclinical hypothyroidism - thyroid function that's "normal" but not optimal - can cause significant cognitive impairment.
Your brain fog isn't in your head. It's in your hormones, your stress response, and your metabolic function.
Why "Normal" Test Results Don't Mean Your Brain Is Fine
"I went to my doctor and mentioned I keep forgetting things. I can't remember anything anymore, or focus. He took bloods, I was told everything looked ‘normal,’ and that hormones were unlikely to be the cause."
Sound familiar?
When you hear “your labs are normal,” what that usually means is that nothing dangerous or overtly pathological showed up. And that’s important to know. But normal doesn’t always mean optimal.
A normal blood test usually means:
Thyroid testing is limited to a single TSH - without looking at Free T3, Free T4, antibodies, or conversion patterns.
Cortisol is tested once and not over the course of the day - even though it’s your daily rhythm that affects you
Sex hormones may not be tested at all, or they’re tested on a random day of the cycle, which makes interpretation tricky.
Standard testing is designed to catch disease, not dysfunction. None of this is wrong. It’s just a different framework - one that focuses on identifying pathology.
The lens I use is a little wider. I’m looking at patterns, timing, rhythm, and how your hormones are interacting with your brain day to day - the subtle functional shifts that can affect how you think, focus, and feel long before anything crosses the threshold into a diagnosable condition.
The Part That Scares Everyone (But Shouldn't)
“What if this keeps getting worse?”
“What if I lose my job because I’m not as sharp as I used to be?”
“What if this is early dementia?”
These thoughts are more common than anyone admits. And when your career depends on your ability to think clearly, articulate ideas, and stay mentally agile, even subtle cognitive shifts can feel catastrophic. It’s not just about forgetting a word.
It’s about identity.
Capability.
Confidence.
But here’s what’s important to understand:
Hormone-related brain fog behaves very differently from neurodegenerative disease.
It tends to fluctuate.
It often coincides with other hormonal symptoms.
And - most importantly - it responds to support.
When underlying drivers like hormone shifts, stress load, metabolic instability, or nutrient depletion are addressed, the internal dialogue often changes to:
"I can think clearly again for the first time in years." "I’m finding my words again." "I can focus through entire meetings without losing my train of thought." "I'm not forgetting everything anymore." "I feel sharper."
Your brain hasn’t suddenly failed you. It's simply struggling to compensate for specific imbalances that can be identified and addressed.
Why Your Brain Is Vulnerable Right Now
Your 40s create a perfect storm for cognitive issues:
You're likely in perimenopause or approaching it, meaning your oestrogen and progesterone are fluctuating wildly or beginning to decline. These hormones have been supporting your brain function since puberty - when they change, your brain feels it immediately.
You've probably been under chronic stress for years (career demands, family responsibilities, being the reliable one everyone counts on). Chronic stress elevates cortisol, which directly damages the hippocampus and impairs prefrontal cortex function.
Your thyroid function may be declining subtly (common in women over 40), slowing down brain metabolism and neurotransmitter production even if you don't technically have hypothyroidism.
Your sleep quality has likely decreased (hello, waking up at 3 AM), and your brain desperately needs deep sleep to consolidate memories and clear out metabolic waste.
You may have nutrient deficiencies (B vitamins, magnesium, vitamin D, omega-3s) that directly affect neurotransmitter production and brain cell communication.
Your blood sugar may be dysregulated, creating glucose spikes and crashes that directly impact focus and mental clarity.
All of these factors compound each other. The more of them you have, the worse your cognitive function becomes.
What Your Brain Fog Is Really Telling You
Different types of cognitive issues point to different underlying imbalances:
Word-finding difficulties and verbal memory problems can often connect to oestrogen fluctuations or decline. The hippocampus and areas of the brain responsible for language are particularly oestrogen-sensitive.
Inability to focus or complete tasks can frequently relate to cortisol dysregulation from chronic stress, or to blood sugar imbalances creating energy highs and lows that affect the prefrontal cortex.
Forgetting why you walked into a room or what you were about to do suggests working memory issues, often related to stress, poor sleep, or thyroid dysfunction affecting processing speed.
Taking longer to make decisions or feeling mentally sluggish may point to thyroid issues affecting brain metabolism, or to chronic stress impairing prefrontal cortex function.
Anxiety along with brain fog often indicates low progesterone (affecting GABA production) or cortisol dysregulation.
Your specific pattern of cognitive symptoms provides clues about which hormones and systems need support.
Why Coffee and Willpower Aren't the Answer
I know what you've probably been doing: drinking more coffee, trying harder to focus, writing everything down, setting more reminders, beating yourself up for "not being sharp anymore."
But here's the problem: You cannot willpower your way out of hormone-induced cognitive dysfunction.
More caffeine might help temporarily, but it's also stressing your adrenal system further, potentially making part of the underlying problem worse.
Trying harder to focus when your prefrontal cortex is impaired by cortisol or thyroid issues is like trying to run faster with a broken leg. The effort isn't the problem - the injury is.
Your brain needs specific support for the specific imbalances affecting it. Not more stimulation. Not more pressure. Actual physiological support.
What Actually Restores Mental Clarity
When we address the root causes of brain fog in women over 40, cognitive function improves - often dramatically:
Supporting oestrogen appropriately (whether through lifestyle changes, targeted nutrition, or for some women with hormone replacement therapy) can restore memory formation, verbal fluency, and mental clarity.
Addressing cortisol dysregulation through stress response support, sleep improvement, and adrenal recovery allows the hippocampus to heal and the prefrontal cortex to function properly again.
Optimising thyroid function (not just getting TSH "in range" but ensuring optimal conversion of T4 to T3 and adequate cellular response) restores brain metabolism and processing speed.
Stabilising blood sugar eliminates the glucose crashes that create brain fog and poor focus throughout the day.
Correcting nutrient deficiencies provides the raw materials your brain needs to produce neurotransmitters and maintain healthy cell communication.
Improving sleep quality allows your brain to consolidate memories, clear metabolic waste, and restore cognitive function overnight.
This isn't about taking supplements and hoping for the best. It's about testing to understand YOUR specific imbalances, then providing targeted support for what YOUR brain actually needs.
The Testing That Actually Reveals What's Wrong
Comprehensive hormone and metabolic testing for cognitive issues includes:
Complete thyroid panel (TSH, Free T3, Free T4, Reverse T3, antibodies) to see not just if your thyroid is working, but how efficiently and whether your body can actually use the hormones it's producing.
Sex hormone testing that captures your patterns across your cycle (or lack thereof), showing how oestrogen and progesterone fluctuations might be affecting your brain.
Cortisol rhythm testing throughout the day to see if chronic stress has flattened your cortisol curve, reversed it, or created other patterns that impair cognitive function.
Blood sugar and insulin markers to identify whether glucose dysregulation is contributing to brain fog and focus issues.
Nutrient testing for B vitamins (especially B12 and folate), vitamin D, magnesium, iron, and other nutrients essential for brain function.
Inflammation markers since chronic inflammation directly impairs cognitive function and can indicate underlying issues affecting your brain.
Once you know what's actually happening, you can address it specifically rather than just hoping your brain fog eventually improves on its own.
What Women Tell Me After Their Brain Clears
"I didn't realise how bad it had gotten until I started feeling better."
"I can participate in meetings without feeling stressed about finding my words."
"I'm making decisions quickly again instead of agonising over every choice."
"My coworkers have commented that I seem different - in a good way."
"I'm not terrified anymore that I'm developing early dementia."
The relief isn't just about thinking more clearly. It's about reclaiming a fundamental part of their identity and capability.
This Isn't Just About Your Brain
Here's what often surprises women when they address the hormone and metabolic issues causing brain fog:
Other symptoms improve too.
When we support oestrogen appropriately, sleep often improves. When we address cortisol dysregulation, energy stabilises. When we optimise thyroid function, weight becomes easier to manage. When we stabilise blood sugar, mood becomes more consistent.
Because brain fog isn't an isolated symptom. It's part of a constellation of issues caused by the same underlying imbalances.
Addressing cognitive function through food and lifestyle means addressing the whole system - which means you don't just think more clearly, you feel better overall.
The Question That Changes Everything
Instead of asking "Am I losing my mind?" or "Is this just what happens in your 40s?", ask this:
"What specific imbalances are affecting my brain function, and how do I address them?"
You're not losing your mind. You're experiencing specific, measurable changes in hormone and metabolic function that are affecting specific areas of brain function in specific ways.
And once you understand what's actually happening, you can work on fixing it.
You're Not Imagining This
Your brain fog is real. Your memory problems are real. Your difficulty focusing is real.
But they're not permanent, and they're not inevitable, and they're definitely not "just part of getting older."
They're your body telling you that specific systems need support. The question is: are you ready to find out what your brain needs?
About the Author
I'm Gráinne Harbison, a nutritionist and functional medicine practitioner who specialises in providing support and comprehensive hormone and metabolic testing for women whose symptoms have been dismissed by conventional medicine. I work with intelligent, capable women in their 40s who know something isn't right-even when they've been told everything is "normal."
If you're tired of being dismissed and want real answers about what's happening in your body, I can help.
