Brain power 

Women know we’re smarter than men. Men likely think the opposite. But what is the real story? Okay, this isn’t exactly a polite conversation for the dinner table… The true answer is that some women are smarter than some men some of the time, and vice-versa. However, there may be some science behind the idea that the female brain is more effective at certain tasks at certain stages of the hormonal cycle than at others, pointing to the possibility that sex hormones can influence our cognitive function.  

Growing a spine 

In the mid-1990s, neuroscientist Elizabeth Gould and her team uncovered the remarkable finding that female mice have different connections between their neurons depending upon their hormonal status. Specifically, when the mice had high estrogen and progesterone levels, they had 30% more dendritic spines on their hippocampal neurons 1. The hippocampus is a key brain region in processing memory and orchestrating cognitive function; so much so that if you do not have a hippocampus, your ability to remember is confined to about the last few minutes 2. Dendritic spines are little outcroppings (spines) on a neuron where one neuron connects with another. They strengthen after a stimulus and are thought of as an anatomical substrate for memory storage. More spines usually means better memory.  

Estrogen and brain health 

However, in this case, it looked like more spines didn’t necessarily mean better memory, just that the strategies used for that memory were different. When navigating around a familiar space when their estrogen levels (and dendritic spines) were high, the mice used a spatial strategy – essentially using their memory of landmarks to navigate. However, when their estrogen levels were low, the strategy differed. In this case they used a response strategy; recalling the positioning of their body in space. Notably, both strategies were equally effective in solving the task and finding their way home 3.  

Female memory 

This is in mice, though. What does this mean for women? Well, interestingly, women also use different strategies to solve cognitive tasks depending on their hormone levels. When navigating a virtual maze, women with high estrogen (and presumably more dendritic spines) remember using landmarks, recalling the location of the virtual trees and virtual ponds. When navigating the same virtual maze when their estrogen was low, they used the same strategy that the mice did; they remembered by recalling their body position in space. Again, success rates were the same, just the strategies were different. It is also interesting to note that these strategies use different parts of the brain 4 and different brain regions are preferentially recruited during different phases of the menstrual cycle 5.  

An intriguing strategy 

Whether success rates might differ if the tasks particularly benefitted from one strategy or the other is an interesting question to explore. There are already suggestions that women are better at verbal memory tasks when their estrogen is high 4 and in tasks involving mentally rotating an image when progesterone is high 6. Likewise, whether men have a similar hormonally influenced cognitive strategy is also worth understanding, especially since men have testosterone fluctuations much more frequently than women do estrogen fluctuations. However, these studies do highlight that having a repertoire of different strategies for solving the same task can add to our success rates. It also highlights that declining estrogen levels, whether through menopause, ovarian dysfunction or other causes, may bring different cognitive strategies to the fore and our flexibility in shifting to use these may be an important point in maintaining good cognitive health.  

References 

1. Woolley et al. Naturally occurring fluctuation in dendritic spine density on adult hippocampal pyramidal neurons. J Neurosci. 1990;10:4035-4039
2. Langer. The history of amnesia-a review. Curr Neurol Neurosci Rep. 2021;21:40
3. Korol et al. Shifts in preferred learning strategy across the estrous cycle in female rats. Hormones and Behavior. 2004;45:330-338
4. Hussain et al. Modulation of spatial and response strategies by phase of the menstrual cycle in women tested in a virtual navigation task. Psychoneuroendocrinology. 2016;70:108-117
5. Hidalgo-Lopez & Pletzer. Fronto-striatal changes along the menstrual cycle during working memory: Effect of sex hormones on activation and connectivity patterns. Psychoneuroendocrinology. 2021;125:105108
6. Shirazi et al. Relationships between ovarian hormone concentrations and mental rotations performance in naturally-cycling women. Hormones and Behavior. 2021;127:104886

from an Expert Author

Sarah J. Spencer

BSc Hons, Ph.D –Neuroscientist

Sarah Spencer is a Professor of Neuroscience of RMIT University. She has around 16 years’ experience investigating the impact of the perinatal environment on brain and behaviour. She has a particular interest in the brain’s immune system and how it governs neurological function.

She completed her undergraduate in Physiology at Otago University in New Zealand and then a PhD in 2004 in Neuroscience at the University of Queensland. She followed this with a three-year postdoc at Calgary University in Canada, studying how exposure to immune challenges in critical programming windows of early life lead to long-term changes in immune regulation and the brain. She then moved back to Australia to Monash University and then RMIT University in Melbourne where she leads her team in the investigation of perinatal programming of long-term brain function.

Sarah has authored and co-authored around 100 scientific publications, including two translating primary scientific studies into articles for children. She is an Associate Editor of one of the top neuroscience journals, Brain Behavior and Immunity, and an Academic Advisory Board member for the Sanfilippo Children’s Foundation, promoting scientific research into this devastating childhood disease.

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