How your menstrual cycle can impact your mental and physical health

While there is certainly evidence that sex hormones do positively (and negatively) impact women’s brains, the historical lack of women’s health research means there is a lot of catching up to do in this area

Dr Máire Finn: ‘The pill suits some women and is horrible for others.’ Picture: Ray Ryan

Thursday, September 1, 1983, is a date that has stuck in my memory for two reasons: it was (a) my first day of secondary school and (b) the day my first period chose to arrive. On the face of it, disastrous timing, but rather than crumble, I coped, happily powering through the day.

Could it be possible that my period helped rather than hindered me? Did the flood of oestrogen fire up my brain? Could those hormones have upped my happiness?

Yes, is the answer. But, as with most things to do with women and their hormones, it’s complicated.

“Menstrual-cycle work is anything but straightforward,” says Dr Pauline Maki, a professor and director of the women’s mental-health research program at the University of Illinois, Chicago.

She explains that research pertaining to the menstrual cycle throws up myriad methodological challenges — such as the importance of having all women being studied at the same point in their cycle, regardless of cycle length — but “excellent, high-quality studies” have been done, and have shown that the rise and fall of hormones during the menstrual cycle do indeed positively impact certain abilities.

“When oestrogen levels were higher, we found increases in verbal fluency,” she says, while other abilities, such as visual spatial skills, were simultaneously negatively impacted.

Verbal fluency is, she says, one area of cognitive ability in which sex difference manifests: “Girls speak at an earlier age compared to boys, they have more complex grammar, their verbal fluency is higher.”

Scientists have long recognised that the hormonal fluctuations of the monthly cycle cause not just physical symptoms, but mental ones too.

When it comes to visual-spatial abilities, however, men consistently outperform women.

“One of the largest biological sex differences that’s been documented in any human system is the difference in the ability to imagine objects rotated in three dimensions,” explains Dr Maki.

If you’ve ever played the video game Tetris, or solved a physical 3D puzzle, you were using mental rotation to visualise how to fit the blocks together. With this type of spatial ability, even when average male-versus-female performance is taken into account, the deviation between sexes is significant, she says.

“[Mental rotation spatial ability] seems to show differences across the menstrual cycle as well, but in the opposite direction of verbal fluency, so that when women are most fluent, when their oestrogen levels are high, their visual spatial abilities are the lowest.”

There’s no need to panic, however. Your Tetris scores aren’t going to drop dramatically at certain times of the month. Skill performance is affected, but these changes are subtle. It’s not a case of ‘I’m suddenly impaired or I’m suddenly not fluent’, Dr Maki says: “It’s just the difference in a couple of words on a verbal

fluency test. Or a difference in a couple more or less correct on those kinds of [spatial ability] tests.”

Scientists have long recognised that the hormonal fluctuations of the monthly cycle cause not just physical symptoms, but mental ones too. And despite the bad press menstruation tends to get — cramps, sore boobs, bloating, anyone? — it has notable positive effects.

“Day one of your cycle is the first day you bleed, usually,” says Dr Máire Finn, a GP at Ennis Centric Health. During the follicular phase of the menstrual cycle, aka the first 14 days of an average 28-day cycle, there is a surge of oestrogen, which, along with other factors, promotes ovulation — the production of an egg — and this is when oestrogen levels peak, she says. During this two-week period, women often feel “more buoyant and positive”, and particularly so at ovulation.

Despite the bad press menstruation tends to get, it has notable positive effects.

Also during this phase, research has shown that the hippocampus — the area of the brain central to memories, mood, and emotions — increases in size and density in parallel with rising oestrogen levels. The implications of this are as yet unclear.

After the egg is produced at around day 14, there’s a progesterone surge, which is the pro-gestation, pro-pregnancy hormone, Dr Finn explains. This is the luteal phase. Once the body realises a pregnancy hasn’t occurred, progesterone drops and a period occurs.

“An awful lot of women get surges of progesterone-driven mood disorders. Moodiness, crying, emotional lability,” she says, adding that they may also feel fatigued, bloated, and hungrier than usual, as progesterone can increase the rate at which food is metabolised.

To put it simply, oestrogen makes us feel good, while progesterone can tend to do the opposite, although its effects in relation to mood can be relatively benign for some.

The effect these hormones can have on mood are particularly relevant when it comes to hormone replacement therapy (HRT) and choosing a contraceptive pill.

“Some people sleep better with progesterone and feel calm with it,” says Dr Finn in relation to that component of HRT. “But maybe about 40% of people are
miserable on it, cranky, tearful, irritable.”

The same applies to the pill. A progesterone-only pill “suits some women, but is horrible for others,” says Dr Finn. The combined pill, which is a combination of oestrogen and progesterone, supplies a consistent level of hormones, “so you don’t have those fluctuations,” she says, and as a result, can help with mood.

“There are about 20, 25 different pills which have different doses, different progesterones and different types of oestrogen, and you mix and match until you find the one that suits [the woman].”

The pill also affects the brain, Dr Maki’s research found. Women taking oral contraceptives showed an enhancement in verbal memory — the ability to recall, say, items on a shopping list.

The pill also affects the brain, Dr Pauline Maki’s research found

So what happens, then, in menopause, when oestrogen levels fall off a cliff? And if exogenous hormones — ie the pill — can enhance verbal memory, is taking HRT a no-brainer for cognition?

Not necessarily. Dr Maki explains that when menopause is medically induced — during IVF, say, or through drugs that treat certain conditions including fibroids — studies have shown that changes occur to the memory circuitry in the brain. Further, when the ovaries are removed, verbal memory is affected, but bounces back with oestrogen supplementation. She says, “I just published a study in BRCA-positive women. When they get their ovaries removed, they show a decline in
[verbal memory]. If they take oestrogen, they perform better than the women who do not.”

Medical suppression of oestrogen, or an oophorectomy, does not necessarily equate to what happens in menopause, though. A study Dr Maki published in 2007 — one of four “five-star, high-quality large randomised trials” — hypothesised that memory would improve with oestrogen supplementation in naturally menopausal women. Dr Maki’s study “randomised those women who went through menopause naturally to hormone therapy or not, and found no benefit whatsoever, counter to my hypothesis.”

Subsequently, another “outstanding” study found “the same thing. No benefit, no harm”. In other words, HRT had neither a positive nor a negative effect on the cognition of menopausal women.

“Despite the chatter in the universe, which would suggest that [HRT] does help prevent dementia,” says Dr Maki. “It didn’t.” She adds a caveat to this. “Our work has shown that the more hot flashes you have, the worse your memory… whether a woman has vasomotor symptoms [ie hot flashes] or not may be a really important determinant of whether hormone therapy improves her cognition, because the hot flashes themselves seem to be harmful for cognition.”

In essence, if you experience a lot of hot flashes in menopause, HRT may be beneficial to your brain health and your cognition. But the benefit is in treating the menopausal symptoms, not the oestrogen deficit.

HRT had neither a positive nor a negative effect on the cognition of menopausal women.

Women who went through menopause early, however, did show an improvement in memory when they went on oestrogen. “So the premenopausal brain, if you will, seems to be receptive to oestrogen generally,” Dr Maki says.

As I said at the outset, it’s complicated. When it comes to how hormones might impact cognition or spatial ability, Dr Maki says it’s too simplistic to say there’s a very straightforward and simple relationship; context is also important. Stress, for example, can affect mood, or sleep, and that in turn can have a knock-on effect on a woman’s ability to perform tasks.

“It doesn’t take a cognitive neuroscientist to tell you that when you’re sleep deprived, it’s harder for you to do challenging things,” she says, adding that research bears that out for verbal memory too.

Another important point to note, she says, is that “all of us might experience the same hormonal changes, but only some of us are sensitive to them”.

“For the menstrual cycle and for menopause, I like to use the mood analogy. We know that there’s this thing called postpartum depression. We know that it affects nine to maybe up to 15% of women. We know that it’s hormonally mediated due to changes in hormones, but not all of us experience it, right? There’s just a small proportion of women for whom changes in hormones really affect them.

If you experience a lot of hot flashes in menopause, HRT may be beneficial to your brain health and your cognition.

“I think if we had the dream study for cognition [in a menstruating woman] we’d see the same thing: that there’s very likely a small percentage of women for whom those hormonal changes do affect their cognition, but it’s probably affecting their cognition within the normal range because they’re young and vibrant, they’ve got healthy brains. So the loss of oestrogen probably won’t make you cognitively impaired.”

The same applies to menopause, she says. “While the loss of oestrogen ‘might make you more vulnerable’ you are ‘not impaired’. I may not be ‘my optimum self’, but I’m not demented,” she explains.

So while there is certainly evidence that sex hormones do positively (and negatively) impact women’s brains, the historical lack of women’s health research means there is a lot of catching up to do.

Also, with studies relating to the menstrual cycle, rigorous controls must be in place for the results to be meaningful and accurate. “There are some studies where they say, ‘one of the weaknesses in our study is that we don’t have hormone levels’. If you don’t have hormone levels, you can’t really speak with confidence that you’ve done the work,” says Dr Maki.