I am also 36 and have been wondering about the same thing. I joke with myself that I'm going senile because I'm too young for that to actually happen (this is correct, right?), but the symptoms aren't funny. I forget what I'm saying as I'm talking, stutter a lot, or can't think of the right word I want to use (basic words like "chicken"). I always feel confused. Sometimes I move like a turtle. It's like my whole brain just doesn't want to function, especially in the speech zone. Typing is totally unaffected.
It feels stress-related but I don't know if you can be so stressed that your mind actually deteriorates to a degree that resembles dementia?? I recently took some mental health screenings and got results for severe depression. I would believe that, I'm much worse off than my usual depression.