Are We (Still) Faking It?: Period-related brain fog

When I first got my period and felt like I’d ‘levelled up’ in puberty, one of the first things I did was download a period tracking app. Immediately, I was met with the option to list my symptoms, and so I scrolled (yes, scrolled!) through the list, ticking them off like achievements. The novelty soon wore off when I was doubled over, struck by cramps that only being knocked out with painkillers could soothe. Ten years on and many painful and mentally taxing periods later, the excitement has somewhat faded, but the list of symptoms persists.

As periods are often perceived as a symbol of womanhood, an unspoken bond, I assumed my experience was somewhat the norm; however, whilst every week before my period feels

like I’m experiencing a personality transplant, I was shocked to find out that only a third of women experience moderate to severe premenstrual syndrome (PMS) symptoms, with less than ten percent of those experiencing severe PMS or premenstrual dysphoric disorder (PMDD) in the UK (learn more in our blog on PMDD). Here, I use ‘women’ when referring to people who experience or have experienced menstruation, whilst recognising that not all women menstruate and some do without identifying as a woman.

Opening up a conversation about premenstrual experiences amongst friends made it

abundantly clear that the extremities I was facing weren’t shared, prompting me to delve into the neuroscience behind PMS. This led to the finding of a study, which grew into multiple studies that concluded that there is a lack of evidence to prove that menstruation significantly impacts cognitive performance - a supposed measure of how well our brains process information. This is thought to be equated to what is commonly experienced as ‘brain fog’, a PMS symptom which encompasses impairments in memory and concentration. I am no stranger to brain fog; every monthly cycle conjures a week of feeling like the cogs in my brain have been smothered in treacle, forgetting words and possessing an increased intolerance to focusing on tasks. With symptoms so profound, and only presenting themselves the week before my period - surely my symptoms are hormone-driven and I have not misdiagnosed myself. Or, have I fallen victim to a placebo effect, the echoes of a longstanding, deep-rooted stereotype? 

Is brain fog just impaired cognition?

Brain fog lacks a clear definition but encompasses behaviours such as difficulty

concentrating, confusion, memory lapses and impaired mental clarity. As it is a rather

individual experience, it is difficult to quantify. It’s therefore often labelled as impaired

cognition for data collection purposes; however, it remains unclear whether the two are equivalent.

Period hormones & the brain

“Women who are more sensitive to hormone fluctuations are probably more likely to experience brain fog, but we don’t know that for sure."- Assoc Prof Caroline Gurvich

Years of research into the days leading up to menstruation have shown that the brain

undergoes structural and functional changes. Though the exact cause of this, and disorders

related to periods, are still unknown, the effects of female period hormones oestrogen and

progesterone are thought to be the most influential, specifically their fluctuations over the 28-day menstrual cycle. The current consensus is that the week before menstruation, when

you’re in your luteal phase, oestrogen drops and progesterone rises, triggering PMS. This is a very simplified summary, and recent studies actually dispute the drop in oestrogen levels, highlighting the severe lack of research into the menstrual cycle.

What’s going on in the brain?

Oestrogen and progesterone have been found to have receptors (where the hormone binds to the neuron) in the amygdala, pre-frontal cortex, and the hippocampus; brain areas involved in cognition, emotional processing and memory. The presence of receptors suggests that oestrogen and progesterone can affect these brain areas. Impairment of their functioning mirrors the description of brain fog. Further research on the amygdala has revealed that the brain region, associated with emotional processing and memory, grows and becomes more reactive in the week before menstruation.

Another study also found that amygdala activity decreases in the presence of the progesterone metabolite, allopregnanolone, during memory encoding. Given the amygdala’s pivotal role in modulating memory formation, the study proposed that memory impairments experienced during PMS stem from amygdala inactivation, which triggers underrecruitment of brain areas that encode and retrieve memories. The amygdala, in essence, is thought to act as a vessel through which memory impairment occurs, as a result of progesterone increases during the week before your period.

Combined, these studies hypothesise that progesterone, acting via the amygdala, could induce mood instability and impairments to the memory encoding process, potentially contributing to what women experience as brain fog before menstruation.

A simplified diagram of what is thought to cause brain fog:

Whilst these studies give us insight into how and why we experience brain fog before a

period, multiple meta-analyses have concluded that cognitive performance is not significantly altered over the different phases. In other words, brain fog might not biologically exist.

Are the stereotypes a myth?

So if our brains are physically changing and a significant number of women report differences in mood and thinking prior to their period, what is going on?

Firstly, concluding that the effects on cognition were insignificant does not mean that there is no effect; it just appears to be small enough that it doesn’t affect the decisions you make or your memory while expecting your period. Again, it’s hard to equate personal experiences of brain fog to measurable ‘cognitive impairments’.

Secondly, the studies claiming the effects were insignificant are meta-analyses, which

analyse data from hundreds of pre-existing papers. They concluded that the research is

either inconsistent, statistically insignificant, or insufficient to demonstrate that a woman’s

cognitive ability changes over her menstrual cycle. However, during data collection, they

focused on women experiencing “normal menstruation” and actively filtered out studies

including words associated with PMS and PMDD. Whilst this may have been done for ease of statistical analysis, it excludes a significant proportion of the population who may, in fact, be more likely to experience brain fog.

Where does this leave everyone outside the parameters of ‘normal menstruation’?

If you thought research into ‘normal’ menstruation was limited, studies on premenstrual

disorders are in their infancy and much more scarce. That said, emerging research seems to be consistent with the idea that people with and without PMS do not experience differing levels of period hormones throughout the menstrual cycle. The theory is that it must be individual responses and sensitivities to the cycling hormones that differ and lead to PMS.

Further research into triggers of PMDD found that individuals who normally experienced

PMDD symptoms were asymptomatic when exposed to constant pre-menstrual levels of

progesterone. It is therefore thought that period-associated fluctuations in hormones trigger

debilitating PMDD symptoms rather than the presence of the hormone itself. An emerging theory associates PMDD symptoms with an altered GABA receptor sensitivity.

Though in its early stages, the research on PMS and PMDD appears to be coming to a

consensus that changes in brain structure and function coincide with changes in period-related hormones. Thus, symptoms associated with the disorders are likely tied to changes in hormone levels before your period. Whether or not cognition is statistically impaired, the chronic fatigue and pain, paired with debilitating mood swings, are bound to alter your ability to think.

The conclusion that ‘normally menstruating women’ don’t experience significantly altered

cognition before a period is not evidence that period hormones don’t affect them at all. It

equally does not mean that misogynistic stereotypes therefore fall onto those who do experience alterations and impairments in cognitive performance, i.e., potentially those outside the brackets of normal menstruation. Both groups of women co-exist, as do endometriosis, polycystic ovary syndrome (PCOS) and irregular cycles, which all appear to be excluded from the aforementioned meta-analysis, despite being closely linked to hormone-related changes in thoughts and behaviour.

It is a sad reality that the only way to liberate one group of women from imposed stereotypes is to isolate another.

What does this all mean?

To answer the question in the title, no, we’re not faking it. The way women react to hormone

fluctuations before their period is an entirely unique experience and appears to manifest as a

spectrum with varying degrees of intensity.

Whether you experience a form of brain fog or not, the stereotype of women on their period thinking irrationally or less efficiently is often weaponised against us, deeming us unfit for roles in leadership or discrediting our ability to work effectively. Being on your period is not a diagnosis, nor is it grounds to question your aptitude.

Evidence that a group of women are behaviourally unchanged when expecting their period

helps dispel the myth that all menstruating women are ‘erratic’ and fall short of regular

cognitive abilities; however, this potential catalyst in shifting societal attitudes towards women needs to be addressed within the context of the large proportion of women who struggle with irregular cycles and who have been consistently disregarded.

There should be no battle of regular vs irregular menstruation, only a spike in momentum

towards better research into women’s health, specifically insights into hormonal and reproductive health. Additionally, addressing brain fog and neurological alterations in response to period hormones within workplaces is a vital next step for validating and accommodating those who do not experience ‘normal menstruation’. 

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This article was written by Lucy Kelly and edited by Rebecca Pope, with graphics produced by Saba Keshan. If you enjoyed this article, be the first to be notified about new posts by signing up to become a WiNUK member (top right of this page)! Interested in writing for WiNUK yourself? Contact us through the blog page and the editors will be in touch.

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