Perimenopausal Brain Fog: A Frequent Complaint That Needs a Compassionate Response, Says Marla Shapiro, CM, CCFP, MHSc

"Where did I put my keys?" It's the type of question many women ask during the perimenopausal period wtih increasing frequency, and increasing anxiety, Marla Shapiro, CM, CCFP, MHSc, a professor in the department of family and community medicine at the University of Toronto, emphasized during an interview with Patient Care at The Menopause Society 2025 Annual Meeting in Orlando, FL, in October.

Cognitive symptoms like brain fog, forgetfulness, and difficulty concentrating are among the most distressing manifestations of perimenopause, often triggering fears of dementia or Alzheimer's disease, she said.

Research validates that these cognitive complaints are real: difficulties in learning and verbal memory are especially common during perimenopause, emerging when menstrual cycles become irregular.1 In the Study of Women's Health Across the Nation, 44% of women in early perimenopause reported forgetfulness, compared to 31% of premenopausal women.2 Shapiro said it is critical to reassure women during this stage of life that these cognitive symptoms are typically transient and often improve as hormone levels stabilize post-menopause.1,3

Fluctuating estrogen levels affect neurotransmission and sleep architecture in the brain, with estrogen receptors abundant in areas responsible for memory and cognitive function, including the hippocampus and prefrontal cortex.1 Both estrogen and progesterone are positively associated with sleep quality during the menopausal transition,4,5 and disrupted sleep can significantly contribute to cognitive difficulties. Understanding this physiological basis helps both clinicians and patients contextualize symptoms and distinguish benign perimenopausal brain fog from more concerning cognitive decline.

In this segment of our interview, Shapiro highlights perimenopausal cognitive symptoms. She provides clear guidance on when to offer reassurance and when symptoms warrant deeper investigation, along with a memorable analogy that helps patients understand the difference.

The following transcript has been lightly edited for flow.

Patient Care: Are cognitive symptoms like brain fog or memory issues prominent during the perimenopause period, and at what point should the clinician maybe think about something else?

Shapiro: So brain fog is something that women will complain about all the time. The notion of brain fog or forgetfulness, trouble concentrating are very, very common during perimenopause, and often they occur because of fluctuating estrogen that influences our neurotransmission and sleep in our brain.

Cognitive symptoms related to perimenopause are typically transient, so they get worse around that period of time. And often, I'll tell women, hang on for the ride. It is going to get a little bit better, and typically it will, as we then lose estrogen entirely.

But if they're persistent, progressive, or functionally debilitating, then you really do need to be looking for other causes. You can have a primary depression that's not just the typical brain fog. So you do have to do a little bit of digging, and you do have to ask questions. You do have to think about neurocognitive disorders.

Women are so fearful about dementia and Alzheimer's that often I'm doing a lot of reassuring. I often joke with women, if you don't know where your keys are, that's fine, but if you find the keys and you don't know what they do, that's a problem.

Perimenopausal Brain Fog: Take-Homes At-A-Glance

Red Flags for Further Investigation

• Persistent symptoms (not cyclical or transient)
• Progressive worsening over time
• Functionally debilitating impact on daily life

Differential Diagnosis Considerations

• Primary depression (beyond typical brain fog)
• Neurocognitive disorders
• Thyroid disorders
• Other medical conditions

Back to Basics: The foundation of distinguishing perimenopause from other conditions is thorough functional inquiry, comprehensive history, and physical examination.

Clinical Pearl: Address the fear first: Many women experiencing perimenopausal brain fog fear dementia or Alzheimer's disease. Acknowledging this fear directly and providing reassurance when appropriate can significantly reduce anxiety. The "keys" analogy offers a simple, memorable way for patients to self-monitor and understand the difference between benign forgetfulness and concerning cognitive changes.

References

1. Weber MT, Maki PM, McDermott MP. Brain fog in menopause: a health-care professional's guide for decision-making and counseling on cognition. Climacteric. 2022;25(6):570-578.
2. Karlamangla AS, Lachman ME, Han W, Huang M, Greendale GA. Evidence for cognitive aging in midlife women: study of women's health across the nation. PLoS One. 2017;12(1):e0169008.
3. Weber MT, Rubin LH, Maki PM. Cognition in perimenopause: the effect of transition stage. Menopause. 2013;20(5):511-517.
4. Haufe A, Leeners B. Sleep disturbances across a woman's lifespan: what is the role of reproductive hormones? J Endocr Soc. 2023;7(5):bvad036.
5. Beccuti G, Ghizzoni L. Sleep disturbance and perimenopause: a narrative review. J Clin Med. 2025;14(5):1479.