See I don't think a poor long term memory is a sign of anything. My sister who SWEARS she's an ENFP (maybe she is, what the fuck do I know, but she seems an awful like an ESTP or an unbalanced ESFP with Te from hell) says she doesn't anything before the age of eight. My mother, an ESFP, thought my sister was lying. "Yes, you do." My mother insisted. My mother is a lot like me. "Remember that time Daddy blah blah blah...and this one time your aunt Donna...ha ha isn't that funny?"
But my sister swears she doesn't remember anything before the age of 8. And I saw another ENFP say he'll probably forget his own son's birth, it's just something he knows about himself. WTF.
Being me, I noticed that before the age of 6-7 EVERYTHING was important (most shrinks will confirm this), then after 7 or 8, selectively, then things were intense during my teens and early 20s, but now I feel like I've been alive so long that I have to let unimportant things go.
I am pretty sure now that this is what John Melloncamp meant in "Jack and Diane" when he says "long after the thrill of living is gone." That line used to make me angry. Hell, I am still thrilled to be alive. But seriously when you're 8 or 16 you really do place a hell of a lot more importance on every single second that happens to you!! And philosophies like Buddhism attempt to "re-teach" us this kind of presence as adults, because you begin to take life for granted at some point in your twenties or thirties, even if you're still doing new things and thrilled to be alive.
I think your brain can only handle so much though like you have to prioritize the "important" things, and "important" things get more and more filtered as you become an adult.
So like I could have dementia at 80 and still be talking to you about my olive green princess phone and the Colgate pump Madness jingle from the mid-1980s and asking you if you'd seen my high school bff.
My grandfather was a fucking brilliant man, and in his final days, sometimes he got up at 5 am and put his work boots to go to work at a job he'd retired from like 15 years earlier.
Of course he was an Si dom, but with me or my mom, I think it would be more like story-telling. I know a semi-senile 82 year old ESTP and he tells the most MAGNIFICENT stories about things that happened 20, 50, 70 years ago. I think I know now at least how SJs and SPs lose their shit...SJs repeat familiar old patterns and SPs tell stories about things that happened 728 years ago.