@mahonlye
I still believe that the confusion arises in the synthetic progestin sometimes being called progesterone and then being confused with a bioidentical progesterone. Synthetic progestin is linked to many conditions including dementia. See studies, the large 2023 Danish study in The BMJ referenced below.
At best most recent studies show no impact either way for most HRT except for negative results when combined with progestin when started 10 years after menopause. see studies listed below.
You might pose the question to copilot which can find all the research and link for you; just remember that even an AI can be confused by the progesterone terminology so you have to be very precise in your phrasing. I programmed for several years so I know how particular and frankly how easily confused a program even AI may become.
To restate in another way with research links:
Recent studies present conflicting evidence, but several analyses suggest that initiated Hormone Therapy (HT) or Menopausal Hormone Therapy (MHT) more than 5-10 years after menopause does not significantly increase, and sometimes shows no link to, the risk of developing dementia compared to no treatment, particularly in studies focused on the timing of initiation.
Key Findings on Timing and Dementia Risk:
No Significant Link/Neutral Risk: A major 2026 review published in The Lancet Healthy Longevity of over 1 million women found no clear evidence that MHT, regardless of timing, significantly alters dementia risk. (link below)
"Timing Hypothesis" Support: Research indicates a "window of opportunity" where starting HT within 5 years of menopause may reduce Alzheimer's risk (30% less risk), while starting 5 or more years after (often >10 years) does not offer the same protection, but also does not necessarily increase risk in all studies.
Contradictory Evidence: Some studies, such as a large 2023 Danish study in The BMJ, argue that any use of combined estrogen-progestin, regardless of age or timing, is associated with a higher risk of dementia, suggesting the brain's response changes with age. https://www.bmj.com/content/381/bmj-2022-072770

Why Later Use May Differ:
Researchers believe that 10 or more years after menopause, the brain may already have early signs of Alzheimer’s, such as plaque accumulation, and introducing hormones at this stage may not provide the same protective benefits observed in early,, intervention.
Latest studies which show little to no impact:
https://www.pharmacytimes.com/view/study-finds-no-evidence-that-hormone-therapy-use-affects-dementia-risk-in-postmenopausal-women
https://www.thelancet.com/journals/lanhl/article/PIIS2666-7568(25)00122-9/fulltext
Recent, large-scale studies and meta-analyses, such as those published in The Lancet Healthy Longevity (2026) and reviewed by the FDA, indicate that HRT is generally neutral—neither strongly increasing nor decreasing dementia risk in older, post-menopausal women.
Contrastingly, The use of "opposed" hormone therapy (estrogen combined with a synthetic progestin) started 10 years after menopause has been associated with higher rates of dementia compared to early initiation.