Women born in the most sexist US states experience a faster decline in memory performance after age 65 compared to those from less sexist regions, new research has revealed.
The difference in cognitive decline between women from the most and least sexist states is equivalent to nine years of brain ageing, according to the study.
Researchers believe sexist inequalities restrict women's access to healthcare and opportunities like education and employment that could help protect against Alzheimer's disease.
The findings suggest addressing social inequities could reduce Alzheimer's burden among women, says Dr Justina Avila-Rieger of Columbia University, who led the research.
Women born in the most sexist US states experience a faster decline in memory performance after age 65
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The study examined "structural sexism" - unequal access to resources and power imbalances stemming from social policies and societal norms.
Researchers calculated each state's level of structural sexism based on male-to-female ratios in the labour force, women in state legislatures and poverty rates.
The analysis included data from 21,000 people across two major American ageing studies.
In 1960, Alabama and Mississippi showed the highest levels of structural sexism, while Connecticut and Vermont demonstrated the lowest.
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The findings suggest addressing social inequities could reduce Alzheimer's burden among women
PAPrevious research has linked structural sexism in adulthood to higher mortality rates and increased chronic health conditions in women.
The exact mechanism of how structural sexism leads to memory decline remains unclear, according to researchers.
"What we do know is structural inequalities shape individual health outcomes by creating barriers to health-enhancing opportunities and resources," explains Dr Avila-Rieger.
"Eventually, these exposures produce disparities in chronic physical health conditions that directly influence brain health, the onset of cognitive impairment and, ultimately, dementia."
Until now, studies examining why Alzheimer's affects more women than men have primarily focused on biological differences like hormones and genes.
The new findings suggest sexism could be an overlooked risk factor for cognitive decline.
In 1960, Alabama, alongside Mississippi, showed the highest levels of structural sexism
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In the UK, women over 65 are twice as likely to have Alzheimer's compared to men, according to the Alzheimer's Society.
While this is partly due to women's longer life expectancy, females over 80 still face a higher risk than men of the same age.
The impact of structural sexism was found to be most pronounced among black women in the US study.
"It is likely that [the] impact of sexism and racism creates a unique form of oppression that has greater salience for cognitive health than sexism or racism alone," says Professor Jennifer Manly of Columbia University.
Dr Sarah-Naomi James from University College London, who was not involved in the study, highlighted the growing research interest in women's historically limited access to education as a potential factor in dementia rates.
The UCL expert emphasised the importance of considering a broad range of life experiences when studying cognitive decline in women.
