No, as I say, most women's brains do adapt over time to having lower oestrogen levels, just as for many women, other symptoms of menopause like hot flushes do stop after a few years. The brain is very adaptable and finds new ways to adjust to lower oestrogen levels, like increasing blood flow. For some women, however, the brain never does quite recover to it's former level but it doesn't mean it goes on declining, other than it would anyway from the general ageing process
You can read more about it here, in a article she wrote in the Guardian recently.
https://www.theguardian.com/society/2024/mar/23/neurology-professor-lisa-mosconi-menopause-brain-book-interview-hrt?ref=mc.newsAt the moment, there is not enough research to say whether HRT helps stave off dementia. HRT has definitely helped my brain function, in particular testosterone and I wish I had started it earlier but I've no way of knowing for sure if I'd be in a better place now if I had. My cholesterol is high, so the blood vessels in my brain are probably clogged up with that!