Why new information is harder to hold onto right now

This is part of a four-week series on the Metabolic Quartet, the four things I check first in every Root Cause appointment. They tend to move together, so this month we’re taking them one at a time. First up: blood sugar.

You listen to something in a meeting and it’s gone five minutes later. You read the same paragraph of an email three times before it lands. Someone tells you a name, and by the time you need it, it’s disappeared. Meanwhile you can still remember your childhood address, your first phone number, the words to songs from twenty years ago.

There’s now a study that explains why this is.

What the evidence shows

A 2026 study in the Journal of Clinical and Experimental Neuropsychology assessed 687 women across the menopause transition: some still having regular periods, some in early perimenopause, some in late perimenopause, and some already postmenopausal. When the two perimenopausal groups were combined, they performed significantly worse on tests of learning efficiency, how quickly new information gets taken in, than women who hadn’t reached perimenopause yet or had already finished it. Their ability to recall things they already knew wasn’t affected in the same way.

The authors read this as perimenopause specifically affecting how new information gets encoded, not memory as a whole. This is a sharper, more useful distinction than “brain fog”, and it gives a specific, real mechanism behind what you’re feeling.

Why this fits the blood sugar pattern

Taking in new information takes a steady fuel supply. Your blood sugar holds less steady through perimenopause, because the hormonal shield that used to keep it in a narrow range through your cycle is thinning (as oestrogen and progesterone levels decline), and underlying metabolic strain that’s often been building quietly for years is revealed. A brain running on an unsteady fuel supply has to work harder to encode new information, even while everything already stored stays intact.

What helps

The study didn’t test interventions, so nothing here claims to reverse what it found. This is what I use with clients, and what tends to help with reducing brain fog symptoms and improving cognitive function.

• Protein at your first meal. Steadier blood sugar through the morning means steadier fuel for whatever you need to take in that day. Your body and brain respond very differently to a protein-focused meal than to a carbohydrate-dominant one.
• Write it down the moment you hear it, not later. The gap between hearing something and needing it is exactly where new information gets lost.
• Protect your sleep. We’ll come back to this properly in a couple of weeks, but poor sleep makes new learning harder at any age, and perimenopause often disrupts sleep at the same time it’s disrupting this.
• Consider using a glucose monitor so you can learn how your body responds to different foods, movement, sleep and stress. A Lingo CGM is used for the first two weeks of my 12-week Menopause Code programme, so you can see if and when your blood sugar levels spike and how this affects brain fog and other symptoms. Then with my guidance we find the tweaks that help smooth blood sugar and help your body and brain work more easily.

Explore next · Free See where it shows up A day in perimenopause: morning fog, the 3pm crash, the 3am waking, and what's driving each. Explore the symptom guide →

This is a dip in how quickly new information is absorbed, not an overall decline in brain function. If you’re worried it’s something more, the British Menopause Society published clinical guidance this year specifically to help distinguish ordinary perimenopausal brain fog from something that needs further investigation.

This pattern is “Brain fog and the words that go missing”, one of the patterns in the interactive symptom map we’ve developed to help you understand your dominant menopausal symptoms. It looks like reading the same page twice, losing a word mid-sentence in a meeting you’re leading. The map shows how it tends to connect to the other patterns that show up alongside it.

Rebalancing your metabolic health supports you through menopause whether you decide to use HRT or not, and it runs alongside whatever you and your GP decide.

Next week: visceral fat, the second driver in the Metabolic Quartet, and what it reveals beyond the number on the scales.