in my post dx nutritional learning curve, i often found i had the same 'a ha' moments several times before i could retain a new piece of information long term.
a number of ms' nutritional knowns can affect cognition. one of the ones i personally found most noticeable was zinc deficiency.
i think my deficient zinc hampered my body's ability to deal with toxic ammonia (a byproduct of just eating). i don't have tests to back up the ammonia suspicion, but my zinc was certainly single digits, and there is research that links low serum zinc and high serum ammonia. "Ammonia, a byproduct of the metabolism of nitrogen-containing compounds, is neurotoxic at elevated concentrations." https://bit.ly/2I3eXMM
(cleveland clinic info)
i prefer serum zinc in the high teens (in umol/l.) although as long as it's higher than serum copper, that is a step in the right direction.
at my worst, in terms of low zinc status, i had next to no short term memory. couldn't remember what show was on if it was the ads. driving became difficult. i have no idea how i continued to function. zinc repletion brought everything back into fighting form and then some. it's been no problem ever since.
i would say my cognitive status is better than it's been in a long time, even going back to before it got really bad. i often used to lose my train of thought when down a conversational tangent. now i consider it a warning sign to shape up my act if that kind of lapse happens.
and that's just one of the nutrients needed to keep the brain in tip top condition