At my lowest point of my life (my covert stutter exploded in disaster) I had an IQ test. Accidentaly it was the same test, exactly the same that I had a few years before. And the result was much lower. I told the prof the fact and he said that I must be lying because if it's true then it's dementia. Anyway, he didn't believe me. Since then nobody could explain me that. IQ can't be lowered by tiredness and like.
Well, it's not dementia, but it's strongly stuttering-related. The most of us can't really react to a thread like this, because we lived our whole life as stutterers, and we can't really tell if we have memory problems or not. We suspect it from time to time though.
We don't remember to our early years because it was traumatic. The very essence of traumas is that you don't really experience them. You block it out, lock it out. That's why our early childhood seems to be a leaky farm on the moon.