smaller hypothalamus found in women on the pill. What implications this will have on other parts of the brain I can't say. I predict that synthetic estradiol does not have the same neuroprotective benefits that the different forms the human body produces does.
Chen, K. X., Worley, S., Foster, H., Edasery, D., Roknsharifi, S., Ifrah, C., & Lipton, M. L. (2021). Oral contraceptive use is associated with smaller hypothalamic and pituitary gland volumes in healthy women: A structural MRI study. PloS one, 16(4), e0249482.
An older study looked at neuroprotection from beta estradiol for specific regions in the hypothalamus, and saw a difference in teh effect from the a-estradiol to b-estradiol in the interactions of the steroid receptor. Granted there are other studies that have found other section of the brain that a-estradiol is more neuroprotective. So perhaps these synthetic hormones are not the best things for women to be taking for years and years. This assumes that women are taking a cycle that has a synthetic estradiol. Lots of the new hormonal IUDs are just synthetic progestins which mean there is literally no neuroprotection.
Goodenough, S., D. Schleusner, C. Pietrzik, T. Skutella, and C. Behl. "Glycogen synthase kinase 3? links neuroprotection by 17?-estradiol to key Alzheimer processes." Neuroscience 132, no. 3 (2005): 581-589.
