As I got into my 30's, I eventually hit a point where my short-term memory was embarrassingly poor. My brain simply wasn't what it used to be. I started taking a multivitamin most days, and it dramatically improved.

A coworker confided similar fears he was experiencing early-onset Alzheimer's or something. I shared that I had similar experiences and getting more vitamins helped.

I don't know which vitamin(s) I was missing, specifically. I don't know how common this is. But a simple daily multivitamin and a consult with a doctor might fix things.