Darn, no one has responded! I thought this was a great question and really wanted to read what someone with direct knowledge would say.
We do emphasize hormonal balance for ApoE4s. Absolutely! In general, when many of us think of hormones we think sex hormones, but there are so many more! Other important hormones include: hormones of the thyroid, insulin, serotonin, cortisol, adrenaline, growth hormone, plus there are many others! I think focus on hormones is more important as we get older, as our ability to manufacture hormones seems to become impaired with the aging process. At your age I think you have more “wiggle room” but I commend your interest and do not dismiss it by any means!
As this is not an area I’m conversant in, I thought I’d just try to give you some direction to I go with.
First, I found this book on Amazon, This Is Your Brain on Birth Control: The Surprising Science of Women, Hormones, and the Law of Unintended Consequences
, by Sarah Hill, published October 2019. I don’t know anything about this book or the author, but it does come with 4.5 stars.
I went to the search engine Google scholar and using "contraception" and "cognition" I got the following results: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C6&q=contraception+and+cognition&btnG=
The very first hit A systematic review of the impact of oral contraceptives on cognition
published in 2014 looks very promising, but unfortunately the full paper is behind a paywall, is it worth $35.95?
I also went to PubMed and got these results:https://pubmed.ncbi.nlm.nih.gov/?term=contraception+and+cognition
They looked so-so to me, but you might want to take a look.
In using the search engine DuckDuckGo (because Google’s vanilla search engine is suspect as it’s been known to bury certain sites, including our own: ApoE4.info) I got https://duckduckgo.com/?t=ffhp&q=contraception+and+cognition&ia=web
Regarding wanting a cycle that is regular, there may be other means of doing that besides a birth control pill. The thyroid also affects the menstrual cycle. Polycystic Ovarian Syndrome is also fairly common, often undiagnosed, and affects menstrual cycles. If you have the time, you might want to watch this video. Dr Nadia Pateguana & Dr Jason Fung – Polycystic Ovary Syndrome
. I was there when this presentation was given and thought it very good, even though my time has passed. Anyway, a l doctor, especially a functional doctor, might be able to help you identify the root cause for your cycle variability.