Oral Micronized Progesterone is Bad for the Brain

No brain harm found: Women taking micronized progesterone alongside estrogen showed no cognitive decline across memory, attention, and executive function over 4 years compared to placebo

Progesterone specifically tested: The study compared brain performance during progesterone use vs. without it — and found no difference, directly challenging the claim

Mood actually improved: Women on oral estrogen + micronized progesterone showed meaningful reductions in depression and anxiety — the opposite of brain harm

Important context: This used micronized progesterone (natural), not the synthetic progestin (MPA) used in the WHI study that raised earlier concerns — these are different compounds with different effects

Bottom line: This well-designed 4-year clinical trial found no evidence that oral micronized progesterone harms the brain, and the regimen including it was associated with mood benefits.

This is a review article, not original research: The paper summarizes findings from the KEEPS trial and its ancillary studies — it does not present new data or statistical analyses of its own, making it ineligible as direct evidence for or against any claim.

The underlying trial is relevant: The KEEPS RCT (n=727) it summarizes found no adverse cognitive effects from hormone therapy including micronized progesterone — but to use that evidence, the original trial paper should be cited instead