I thought it was clear. The amount of estrogen women have post menopause is a fraction of what they had before. Men's testosterone declines gradually, all their lives.
Women can lose up to 25% of their bone density in first 5 years immediately after the menopause directly related to estrogen loss.
There are many experts (consultants in neurology for example) who are certain that the menopause can contribute to dementia, because far more women suffer from dementia than men. One such expert was interviewed in a TV programme a couple of years ago (might have been the one with Mariella Frostrup. )
There are never going to be random controlled, double blind trials on HRT.
Partly as there is no incentive financially for pharma (HRT is dirt cheap and the money is in cancer drugs, obesity drugs, etc.)
But also because how many women would be happy to take an unknown 'drug' (HRT or a placebo) for 20 years to see how it affects them?
All research is going to be retrospective and observational.
But the fault with this current research is the HRT used was 20 years ago, compared to newer types. And there were many lifestyle factors- like exercise- which were excluded.