Over the last few years I’ve noticed changes in my cognitive function, with a big drop-off in the last year specifically.
I’ll walk into a room and forget why. I can’t remember people’s names or words I use daily. When my focus scatters, it feels less like my familiar noisy ADHD brain running 16 programs at once, and more like someone has jammed their fingers into my thought and pulled it in 5 directions. I try to hold onto it, but it just evaporates. Some days my brain is relatively sharp and capable, and other days it feels like I’m thinking through wet sand and everything takes 5 times longer than it should. If you’re somewhere in the perimenopause years or have ever suffered from brain fog, I bet you know exactly what I’m describing.
When your brain stops feeling like yours, everyone has a different explanation. It’s stress. It’s hormones. It’s your thyroid. It’s your gut. It’s burnout. It’s “just where you are in life.” What I have found in this situation personally is what I usually find with my metabolic health clients — there’s not just one smoking gun — there’s usually a little of column A, a little of column B, and C, and so on. Which is exactly what makes a solution so hard to pin down. And why it helps so much to work with someone who takes your whole health and habit history into account, not just one piece of it.
I’ll be honest with you about where I’m writing this from. I’m in it right now. I have ADHD that went undiagnosed until my thirties. I got sober at 40 — which, looking back, was probably right around when perimenopause was quietly beginning. For most of my life, alcohol numbed a lot of the noise in my brain. When I got sober, that noise came roaring back: sixteen thoughts firing at the same time, all day long, significantly worse than when I was drinking. At first I assumed I was just finally feeling my own mind without anything dampening it. But the timing matters too — sobriety and perimenopause arrived together, and I’ve come to believe they’ve been tangled up ever since. Add in a period of grief unlike anything I’ve ever experienced just over a year ago, and the subsequent (and probably related) gut infection trifecta I’m currently working through that’s been wreaking havoc on my energy and clarity, and you can see why untangling what’s driving what isn’t simple.
But I’ve learned, both in my own body and in my work with clients, that you don’t have to perfectly isolate and diagnose every contributing factor to start feeling better. Because they’re all synergistic anyway. The brain isn’t a mystery floating separate from the rest of you. It’s a metabolic organ. And once you understand what’s actually happening to it during this transition, the path forward — even a messy, in-progress one — gets a lot clearer.
Let me walk you through it.
My name is Alisa Turner and I’m a certified integrative health coach specializing in nutrition planning, fitness, and overall well-being. If you’re ready for clarity and a sustainable approach to a healthier life, I’m here for you. Contact me!
Your Brain Is a Metabolic Organ
We tend to think of the brain as separate — the command center sitting up top, running the show while the body does the physical stuff. But your brain is one of the most metabolically demanding organs you have.
It’s about 2% of your body weight, and it burns roughly 20% of your energy. It’s also extraordinarily mitochondria-rich — your neurons are packed with these tiny cellular engines that turn food and oxygen into usable fuel. Thinking, focusing, remembering, and regulating your emotions all take an enormous amount of energy, and your brain has very little ability to store fuel of its own. It needs a steady, moment-to-moment supply.
For most of your life, that supply comes primarily from glucose. Your brain pulls sugar from your bloodstream almost constantly, and it relies on insulin signaling and healthy mitochondria to convert that glucose into ATP — the actual energy currency your cells run on. For decades, the system hums along. You feel clear, focused, steady.
But in perimenopause, that system starts to wobble — and the reason why is one of the most overlooked facts about this entire transition: estrogen is deeply involved in how your brain produces energy. It helps your brain take up and use glucose efficiently. So as estrogen begins to fluctuate and decline, your brain’s ability to fuel itself the way it always has starts to falter. Blood sugar feels harder to keep steady, insulin resistance can creep up, mitochondria become less efficient, and your brain — that energy-hungry, fuel-dependent organ — is often the very first place you feel the dip.
This is why a blood sugar crash shows up as fog and irritability, why one bad night of sleep can leave you searching for words the next day, and why chronic stress — which hijacks your energy and floods you with cortisol — makes it so hard to think clearly. In perimenopause, all of that gets amplified, because the hormonal buffer that used to keep your brain’s energy system stable is changing.
If you’ve followed my work, you know I talk about metabolic health constantly — protein, muscle, mitochondria, blood sugar, sleep, nervous system regulation. Your brain is part of that same conversation. It isn’t separate from your metabolism. It’s arguably the organ most sensitive to it.
Which means the brain fog and the mood swings aren’t happening in spite of good metabolic health; rather, they are one of the earliest signals that something in your metabolic foundation needs attention — your brain may just be the first place you feel the shift. And the research on exactly what’s happening in the perimenopausal brain is honestly fascinating.
What’s Actually Happening in the Perimenopausal Brain
For a long time, “menopause brain” was treated as a complaint, not a condition. Women reported brain fog, forgetfulness, trouble focusing, and mood swings, and were told it was stress, aging, or all in their heads. But in the last several years, neuroscientists — most notably Dr. Lisa Mosconi at Weill Cornell — have actually imaged the menopausal brain, and what they found changes the whole conversation.
Using brain scans (PET and MRI) on women across the menopause transition, researchers documented something striking: the brain physically changes during perimenopause, in measurable, specific ways. And — this is important — these changes were tied to the menopause transition itself, not just to getting older. When researchers compared women to men of the same age, the men’s brains didn’t show the same shifts. This is a female, hormone-driven process.
Here’s what the imaging showed:
Brain energy metabolism declines. As estrogen drops, the brain’s ability to use glucose efficiently goes down (a pattern researchers call cerebral hypometabolism) leaving less efficient fueling in the very regions responsible for memory, attention, and higher-order thinking. The studies show a measurable dip in how well the brain is generating energy.
The brain starts switching fuel sources. When glucose metabolism falters, the perimenopausal brain begins leaning more on ketones as a backup fuel. This is an adaptive move — your brain is problem-solving its own energy crisis. But the transition period, while your brain is figuring out this new fuel strategy, is often when women feel the most cognitively “off.”
Gray matter volume drops. Hear that — the brain regions involved in memory and processing actually lose volume during the transition. That sounds alarming — and if it were the end of the story, it would be.
For most women though, the brain adapts. Mosconi’s research found that after the transition, brain biomarkers largely stabilized. Gray matter recovered in key regions. Energy production (ATP) actually increased in some areas post-menopause, and that increase correlated with preserved cognitive performance. In other words — the perimenopausal brain isn’t breaking down permanently. It’s just reorganizing. It’s going through a vulnerable, turbulent renovation, and then, for most women, it comes out the other side stabilized and functioning well.
There’s one group that deserves extra attention: women who carry the APOE-4 gene variant (the biggest genetic risk factor for Alzheimer’s) showed more amyloid buildup during the transition. This doesn’t mean perimenopause causes Alzheimer’s. It means that for women with that genetic risk, the menopause transition appears to be a particularly important window to support brain and metabolic health proactively. If Alzheimer’s runs in your family, this is worth a conversation with your doctor about testing and early intervention.
I find this research genuinely reassuring because it confirms that what you’re feeling is real and physiological. You are not imagining things, nor are you failing or losing your edge. And it’s not “just stress” or “just aging.” The research also reframes perimenopause as what it actually is: a neurological transition, not the beginning of a decline. A turbulent transition, yes. But one your brain is, in most cases, built to move through and adapt to.
So what’s driving the way you feel day to day, and what can you do about it?
Once you understand that perimenopause is a metabolic and neurological transition, a lot of the symptoms that feel random or alarming start to make sense as different expressions of the same underlying shift rather than separate problems.
If you’re experiencing any of these, here’s what’s likely happening underneath, and then we’ll get to those solutions:
Brain fog and word-finding trouble — your brain’s energy supply is less efficient, especially in regions handling memory and language. When fuel delivery dips, those are some of the first functions to feel it.
Emotional volatility and a shorter fuse — estrogen helps regulate serotonin and dopamine, and progesterone has a calming, GABA-like effect. As both fluctuate, your emotional baseline gets shakier. Others may tell you you’re “just being too sensitive” — but your neurochemistry is genuinely less buffered right now.
Anxiety that seems to come from nowhere — estrogen helps blunt cortisol, your main stress hormone. As estrogen declines, that buffer thins, so the same stressors hit harder and your system stays activated longer.
The “flat,” unmotivated feeling — dopamine signaling shifts during this transition, which can dull drive, motivation, and the sense of reward you used to get from things you enjoyed.
Sleep that falls apart — progesterone supports sleep, and as it drops, falling and staying asleep gets harder. Poor sleep then worsens everything else, because sleep is when your brain clears metabolic waste and consolidates memory.
Memory blips that didn’t used to happen — the hippocampus, your memory hub, is dense with estrogen receptors, so it’s especially sensitive to estrogen’s decline.
It’s scary, I know. And sometimes it genuinely feels like you’re losing your mind. But each one traces back to a real, physiological shift. And if you’re someone who, like me, also has ADHD, a history of addiction, chronic stress, or a gut issue layered on top — these effects compound and amplify each other, which is exactly why it gets so hard to tell what’s causing what.
That tangle is real. But you don’t have to isolate every single thread to start improving things, because most of these levers respond to the same foundational support.
How to Support Your Brain Through the Transition
If the perimenopausal brain is struggling with energy, then supporting your brain is largely about supporting your metabolism. The same foundation that stabilizes your blood sugar, protects your muscle, and calms your nervous system is what gives your brain the fuel and the conditions it needs to move through this transition well. If you’ve been coached by me before, and you’re just starting to feel these things, this should feel like a relief — because we’ve already been through a lot of it. Repeatedly. Now we just add a few extra tools.
I think about it in layers — and I’m actively working through some of these layers myself right now, not writing from a totally finished, figured-it-out place. But this is the order I’d build them in.
Layer 1: The Metabolic Foundation
This is the layer most people want to skip, and it’s the one that matters most. Nothing else works as well without it.
Protein at every meal. Aim for 30-40g. Protein gives your brain the amino acid building blocks it needs for neurotransmitters like dopamine and serotonin, and it keeps your blood sugar steady so your brain isn’t riding a glucose roller coaster all day.
Strength training, 2-4x a week. If you follow me, you may be tired of hearing me hammer home the importance of progressively overloading your muscles. But working muscle releases compounds that support brain growth and protect cognition. It also improves insulin sensitivity — so your brain fuels more efficiently, and builds the metabolic reserve that carries you through this turbulent transition.
Stable blood sugar. Every crash is a hit to your brain. Pairing protein, fiber, and fat — and not letting yourself get ravenously hungry — keeps your energy and your focus far more even. In this season of life, I’ve had to shorten the gap between feeds. Every 4 hours, I need something in my system. Hard stop.
Sleep, protected fiercely. Sleep is when your brain physically clears metabolic waste and consolidates memory. It’s not a luxury or a willpower issue. In midlife, you genuinely cannot out-supplement or out-train poor sleep. I used to be able to function fairly well on 6 or 6.5 hours a few days a week, as long as I could catch up on the weekends. Those days are gone. I need 7.5 hours of recorded sleep nightly, more if I’ve had a high-strain day, or my brain pays the price the next day.
Omega-3s, especially DHA. Your brain is largely built from fat, and DHA is a structural component of brain tissue. This is one of the most evidence-backed nutrients for brain health there is. I increased mine and now get a minimum of 2g per day combined DHA/EPA.
Layer 2: Nervous System Support
The perimenopausal brain is more reactive to stress, because progesterone’s calming, GABA-supporting effect is dropping. There’s literally less stress buffer there from hormones. That means stress regulation isn’t “nice to have” anymore — it’s part of your brain-care plan.
Daily downshifts: long-exhale breathing, morning sunlight, walks after meals, a few scheduled and intentional quiet minutes that aren’t filled with input.
Active recovery on non-lifting days — walking, yoga, gentle movement.
Reducing the overstimulation where you can. Turn off the notifications on your apps. Switch your ringer to silent — 24 hours a day, and only check it during scheduled times. Do your walks without your phone. Unsubscribe to all the junk email regularly. Unfollow or mute social media accounts you don’t really need to hear from. It’s not forever — it’s just a season. Your nervous system can only receive support when it isn’t under constant stimulation.
This is the layer I personally find hardest, and the one that pays off the most when I actually honor it.
Layer 3: Targeted Support
Once the foundation is in place, this is where I start asking what’s specifically struggling for a given person — and where some of the most interesting brain-supportive tools come in.
Creatine — not just for muscle. Emerging research points to cognitive benefits, especially for women and especially under stress or sleep deprivation.
Magnesium (glycinate or threonate) — supports sleep and calm, and threonate specifically is studied for cognition.
B vitamins, particularly methylated forms — essential for making neurotransmitters and managing stress.
Mitochondrial support — this is the layer I’m most fascinated by, since so much of the perimenopausal brain story is really a mitochondrial energy story. Tools like NAD+ and various peptide therapies are being explored here.
Layer 4: Hormones
For a lot of women, this is a significant piece, because the root of so many of these brain changes is the loss of progesterone’s and estrogen’s support. Hormone therapy is one of the most studied interventions for perimenopausal cognitive and mood symptoms, and timing appears to matter — starting during perimenopause seems more beneficial than starting years into post-menopause.
I’m navigating this myself, and it hasn’t been a simple plug-and-play fix. I had to switch from having my OBGYN managing things to a dedicated hormone specialist. There’s been 2 rounds of tweaking already, and we are still “in process.” Hormones interact with your gut, your thyroid, your stress load, and each other, which is exactly why this is a conversation to have with a knowledgeable provider who looks at the whole picture — not a one-size protocol. But for many women, at the right point in the transition, it can be a meaningful part of the plan.
A Note on Thyroid and Gut
I want to name two things that often hide underneath “brain fog” and get missed: your thyroid and your gut. Low thyroid function can look exactly like perimenopausal brain fog and fatigue. And gut issues — infections, dysbiosis, low microbial diversity, which themselves can worsen as estrogen drops — affect mood, inflammation, and how well you absorb the nutrients your brain depends on. If you’ve dialed in the foundation and still feel off, these are worth investigating with the right labs and the right provider. (I’m in the middle of exactly this myself, which is part of why I know how tangled it can get.)
You’re Not Losing Yourself
If you only take one thing away from this article, I hope it’s this (and I have to tell myself this on the regular): the way your brain feels in perimenopause is not a sign that you’re declining or losing who you are. You’re just in the middle of a real neurological transition — one with a murky beginning, a turbulent middle, and, for most women, an adaptation on the other side.
You don’t need to white-knuckle your way through a decade of your life hoping it passes. The women who move through this best are the ones who understand what’s happening and support the foundation underneath it (the protein, muscle, sleep, blood sugar, nervous system, and hormones) so their brain has what it needs to do the reorganizing it’s built to do.
I’m writing this from inside my own version of the tangle. Some days my brain feels clear, and some days it doesn’t. The trajectory is good, but I haven’t figured all of it out — I’m working through the layers right alongside you, as well as with my providers and my own trial and error. But I’ve stopped worrying that something is wrong with me, and I most definitely have not accepted cognitive decline as an inevitable part of being in mid-life. These symptoms are all just data and a signal to support my body differently for the season I’m in.
That shift — from “what’s wrong with me” to “what does my body need right now” — is where everything starts to change. Because while sometimes it can feel like your body and your brain are betraying you, they’re really just asking for a different kind of support than it used to need. And you’re allowed to give it that support without waiting until you’ve perfectly diagnosed every cause.
You’re not losing yourself. You’re transitioning to an upgraded version of yourself — and she’s worth taking care of.
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If you’re in this season and want help building the foundation that supports your brain, your metabolism, and your hormones, and find the right providers who will listen and spend the time needed to optimize — that’s exactly the work I do with clients. Here are a few ways to start:
Comment HORMONES on any of my Instagram posts, and you’ll receive a link to my free Perimenopause Metabolic Reset Guide — the initial and simple daily shifts I start clients with for steady energy, stable blood sugar, improved body composition, and a clear mind.
Curious about the mitochondrial and peptide piece I mentioned? I wrote a full post on that here: Peptides Beyond GLP-1: What Supports Your Metabolism, Energy, and Longevity.
And if you’d rather talk it through directly, you can book a free consultation. Mount Pleasant, SC + virtual.
A Gentle Reminder: I’m a functional nutritionist and metabolic health specialist, not a physician. Everything here is education and personal experience, not medical advice. Perimenopause, brain symptoms, thyroid, gut, and hormone therapy are all worth exploring with a provider who knows your full history. Please don’t start, stop, or change any protocol without talking to your doctor.
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