‘Period brain’ may be one of the mainstays of internet banter – but a new study doesn’t find any scientific evidence for it
What is the scientific evidence that having a period affects cognitive ability? (Picture posed by a model.) Photograph: fizkes/Getty Images/iStockphoto
Is there such a thing as period brain? There are teams of researchers asking exactly what having a period does to your memory, ability to pay attention and your judgment. So far, the weight of studies has been firmly tilted towards fluctuating levels of hormones during the menstrual cycle having both physical and mental impacts. The authors of a review in the Archives of Gynaecology and Obstetrics state: “The effects of the menstrual cycle on emotional state and cognitive function have been long recognised,” and cite internet humour as confirmatory.
Banter on the internet doesn’t make period brain a real thing. And a new study in Frontiers in Behavioural Neuroscience doesn’t support the theory either. It’s not a big study – only 88 women were enrolled – but studies in this field are often small, some with as few as 10 women.
These women had their levels of oestrogen, progesterone and testosterone measured and analysed for any association with how they performed in tests of cognitive function at different times in their menstrual cycle. They then went through the same tests again for a second consecutive month. There was an association found in the first round of tests between the memory we use for reasoning and to make decisions (working memory) and levels of progesterone, but this was not found in the second cycle.
Brigitte Leeners, a professor of reproductive endocrinology at the University hospital in Zurich, is clear that there was no association found between hormone levels and how well the women did in their cognitive tests.
The study did not investigate if women feel mentally below par due to having stomach cramps or feeling tired – this was simply about hormones. Leeners says in her paper that scientific dogma states that oestrogens are involved in attention and working memory. However, she believes the studies showing this link are not robust and often based on small numbers of women. As far as her paper shows, there is no link between cognitive function as measured through testing attention, reasoning and decision making.
Leeners does say that there may be some individual sensitivities to hormone levels, which her study might not have picked up. It also did not look at emotional changes, and previous studies have found that high levels of progesterone are associated with more activity in the part of the brain called the amygdala, which increases how much we retain or recall emotional memories. Other studies find up to 10% of women have severe premenstrual symptoms.
This latest study does not say that periods aren’t hell for some women, but it does find that any changes in how well our brains work on the basis of hormone levels (not in how we feel) are either small, hard to find or nonexistent.