Brain fog is inevitable with CF. In an effort to keep it at bay, three years ago I learned to use the computer. I used to be a fast learner, but now if I learn one new function a day (and not forget how to use the one I learned 2 days ago), I'm satisfied.
Something else I've learned the hard way is not to expect too much of myself. I can, for the most part, look after myself, but can't take on much more.
Like the rest of you with "fibro fog", I've learned to go easy with my expectaions of my capabilities.
There is no way in he** that I could go jogging, running and do jumping jacks. Those were things I took for granted, but no more. That's way back buried in the past (where it's probably going to stay).
I have learned many things about the computer, but as my memory is no longer capable of absorbing much at one time, one function a day is the most I can hope for.
I do take ginkgo biloba twice a day, and I think that helps a little, but I'm not certain.
Just to give you an idea of the change in my cognitive capabilities, I taught senior English to grades 11 - 13 studying authors such as Shakespeare, Dickens and Thomas Hardy. After my diagnosis of fibro, I couldn't understand even the simplest novel, and started with The Reader's Digest and People magazine (lots of pictures!!). Right now, my capabilities are higher and John Grisham my favourite author.
Your memory will improve given time, but meanwhile, be kind to yourself