To be frank, i had been doing this from my childhood, up until extreme Now i lost all abilities and developed severe ocd adhd.

Not sure its same context, but i had been using visual imagery to memorize full books 100s of pages alphabet by alphabet not one punctuation here and there.

Initially it was very strong imaginery capabilities that i later during my academic years put use to it for memorising purpose.

To explain consider i was like taking photos through my eyes, whole books as has been scanned within my brain. And i could recall them in an instant, ask any question from anywhere within book and i instantly generate answers in my brain with such speed that my hands could not cope up writing it down without compromising on handwriting.

But now for last 7 years i lost all those in an instant now i could'nt remember a sentence after hour unless i keep repeating or write it down.