We already know sexism is bad for womens paychecks, as women are paid 84% of what men are paid on average. We also know its historically been bad for womens mental health. But now, were learning that it could be harmful in ways we hadnt even realized.A new study found women born in the most sexist U.S. states experience faster memory decline later in life, compared to women born in the least sexist U.S. states, according to a researchers at Columbia University Vagelos College of Physicians and Surgeons.The study measured sexism over six decades, from 1900 to 1960. Each states level of structural sexism was calculated based on male-to-female ratios in the labor force, the number of females in state legislatures, poverty rates, and other factors like inequality in resources and power that stem from social policies and societal norms. The state with the highest structural sexism was Mississippi in 1910, and the lowest was Connecticut in 1940, study leader Justina Avila-Rieger told Fast Company.For women born in those two example cases, the difference between their cognitive decline after age 65 was a staggering 9 years, or nearly a decade.The findings are particularly important because women are disproportionately affected by Alzheimers disease in the U.S. Nearly two-thirds of Americans currently living with Alzheimers are women, and women also make up some 60% of Alzheimers caregivers, partly due to the fact that women live longer than men, and the risk of developing dementia increases with age.The study, Early Life Exposure to Structural Sexism and Late-Life Memory Trajectories Among Black and White Women and Men in the U.S., was published Wednesday online in Alzheimers & Dementia: The Journal of the Alzheimers Association. It looked at relationships between structural sexism and memory performance among 21,000 people in theWashington Heights-Inwood Columbia Aging Projectand theHealth and Retirement Study, and found the connection was highest among Black women.The research adds to a growing body of studies looking at the relationship between structural sexism and womens health. Previous studies found women who endured greater structural sexism in adulthood had higher rates of mortality, increased risk of chronic health conditions, and less accessible and affordable healthcare.