Sexism is still too often dismissed as a series of “minor inconveniences”: an inappropriate joke, a comment about appearance, being interrupted in meetings, workplace infantilization, daily mansplaining, constant doubt cast on women’s competence.
But a large-scale international scientific study published in Proceedings of the National Academy of Sciences (PNAS), based on 7,876 brain scans across 29 countries, suggests a far more serious reality: gender inequality is not only a social injustice. It may also be associated with measurable structural differences in the brain, with one central mechanism repeatedly highlighted by researchers: chronic stress.
https://www.pnas.org/doi/10.1073/pnas.2218782120
Crucially, the researchers also underline a broader and well-documented pattern: in countries with higher gender inequality, women face higher risks of mental health problems and lower academic achievement compared with men.
https://pubmed.ncbi.nlm.nih.gov/37155867/
In societies where the everyday impacts of sexism are still minimized, this research raises a difficult but essential question: what does inequality do to women when it becomes a permanent environment rather than an isolated incident?
A rare global dataset: nearly 8,000 brain scans across 29 countries
The researchers conducted a large meta-analysis of 7,876 MRI scans (healthy adults) drawn from 29 countries across 139 samples, including 4,078 women and 3,798 men.
https://pubmed.ncbi.nlm.nih.gov/37155867/
Their goal was to assess structural brain differences between women and men, and then determine whether those differences vary depending on the level of gender inequality at the country level.
This is what makes the study particularly significant: it moves beyond a single local population and instead connects neuroscience, cross-country comparisons, and social environments.
How gender inequality was measured at the country level
To examine gender inequality, the researchers relied on internationally recognized measures used in global comparisons.
Two reference frameworks are especially relevant for understanding this work:
The Gender Inequality Index (GII) from the United Nations Development Programme (UNDP), which captures gender-based disadvantage across reproductive health, empowerment, and labour market participation.
https://hdr.undp.org/data-center/thematic-composite-indices/gender-inequality-index
The Global Gender Gap Index from the World Economic Forum, assessing gender gaps across economic participation, educational attainment, health, and political empowerment.
https://www3.weforum.org/docs/WEF_GGGR_2023.pdf
These global rankings serve as a reminder that gender equality is not just a cultural debate: it is measurable, comparable, and deeply tied to real-life outcomes.
What the study measured: cortical thickness as a key marker of brain structure
The study focuses on one structural measure frequently used in neuroscience: cortical thickness.
This indicator is often used to explore whether life conditions and environmental exposures—including chronic stress and adversity—are associated with structural variation in the brain.
The main findings: in more unequal countries, some brain regions appear relatively thinner in women
The study reports that in several brain regions, sex-related differences vary depending on the level of gender inequality in the country.
In more equal countries, these regions show limited structural differences between women and men, or sometimes relatively thicker cortex in women. In more unequal countries, cortical thickness is relatively lower in women compared with men.
https://pubmed.ncbi.nlm.nih.gov/37155867/
The key regions identified include:
- right caudal anterior cingulate
- right medial orbitofrontal cortex
- left lateral occipital cortex
https://pubmed.ncbi.nlm.nih.gov/37155867/
These regions are often involved in emotional regulation, stress-related processing, resilience, and mechanisms linked to mental health vulnerability.
A readable synthesis of the findings is also available here:
https://www.clinicbarcelona.org/en/news/differences-are-found-in-the-brains-of-women-and-men-living-in-countries-with-gender-inequality
Mental health: the missing link in public conversations about sexism
The point of the study is not to claim that women’s brains are “naturally inferior” or biologically predetermined.
Its significance lies in the opposite direction: it suggests that a social environment shaped by inequality may be associated with measurable structural outcomes, consistent with the idea that long-term adversity can affect the brain.
The authors explicitly note that gender inequality is linked to higher risks of mental health problems for women.
https://pubmed.ncbi.nlm.nih.gov/37155867/
In real life, that pressure is rarely one single traumatic event. It often builds through cumulative, persistent exposure:
- everyday humiliation and dismissal
- harassment in public spaces
- objectification and constant scrutiny of women’s bodies
- workplace discrimination and glass ceilings
- unequal domestic labour and mental load
- fear, insecurity, and chronic vigilance
Work and pay: inequality is not abstract, it is structural and exhausting
Gender inequality is also built in workplaces through leadership access, credibility, pay gaps, and tolerated discriminatory behaviours.
And in Europe, a major shift is coming: the EU Pay Transparency Directive introduces new obligations on pay transparency, aiming to reduce gender pay gaps and strengthen enforcement.
Official EU text: https://eur-lex.europa.eu/eli/dir/2023/970/oj
Education: gender inequality also reduces women’s academic trajectories
Beyond mental health, the study highlights another powerful association: in more gender-unequal countries, women tend to show lower academic achievement compared with men.
https://pubmed.ncbi.nlm.nih.gov/37155867/
This does not reflect ability. It reflects unequal conditions.
In the most unequal contexts, barriers frequently include:
- unequal access to education and resources
- gender stereotypes shaping academic choices
- early domestic responsibilities
- interrupted schooling
- early marriage or early motherhood
- gender-based violence and weak institutional protection
- fewer female role models in high-status fields
The result is a reinforcing cycle: fewer degrees, less economic independence, increased vulnerability, and reduced ability to escape unsafe or discriminatory environments.
Sport, politics, and social media: the same mechanisms of violence and disqualification
Sexism is not limited to work or home life. It extends into sports, public life, and politics, where women are still disproportionately targeted through appearance-based attacks, harassment, and credibility challenges.
On sexism faced by women athletes, read also:
https://www.thewomensvoices.com/news/sexism-and-barriers-the-hidden-reality-for-women-athletes/
On women’s leadership and the way it is perceived and contested, read also:
https://www.thewomensvoices.com/interview/yael-braun-pivet-i-believe-female-leadership-is-different/
On online sexism and digital violence, read also:
https://www.thewomensvoices.com/news/the-alarming-rise-of-sexism-on-youtube/
“A scar on the brain”: a phrase that forces a shift in perspective
In media coverage of the research, psychiatrist Nicolas Crossley described the findings through a striking idea: inequality may leave a lasting mark—like a “scar”—on the brain.
The scientific point is not metaphorical sensationalism: it captures how inequality can function as a chronic social exposure that becomes biologically relevant.
What the study does not claim: avoiding bad science and oversimplification
This study does not prove that women’s brains are naturally inferior. It does not claim that every woman will be affected in the same way.
It identifies a robust association between country-level gender inequality and structural brain differences, and it supports an interpretation consistent with social exposure: less favourable environments for women may contribute to these differences through chronic stress and other factors.
https://www.pnas.org/doi/10.1073/pnas.2218782120
Why this research shifts the political meaning of gender equality
The authors highlight a strong implication: the development of “neuroscience-informed policies”.
https://pubmed.ncbi.nlm.nih.gov/37155867/
In other words, gender equality is not only a moral goal or a cultural debate. It is also a matter of public mental health, education, economic independence, and long-term social stability.
Reducing inequality, fighting gender-based violence, protecting women’s rights, securing educational and professional pathways, and challenging discrimination are not symbolic gestures: they are structural interventions that shape women’s lives—and potentially their mental health.
On the role of male allies and why silence matters, read also:
https://www.thewomensvoices.com/news/tribune-mens-silence-must-end-says-un-women-france/
Key takeaways
A 2023 study published in PNAS, based on 7,876 MRI scans across 29 countries, links gender inequality to structural brain differences observed in women across specific regions.
https://www.pnas.org/doi/10.1073/pnas.2218782120
The authors also highlight that higher gender inequality is associated with higher risks of mental health problems and lower academic achievement for women compared with men.
https://pubmed.ncbi.nlm.nih.gov/37155867/
Together, these findings reinforce a message too often ignored: sexism and inequality are not superficial. They can become chronic pressures that shape women’s mental health, educational paths, and long-term opportunities.