I think Syd had ‘natural’ so to speak, mental issues but unless I am mistaken, wasn’t he more an acid casualty? I remember stories about him combing crushed up qualudes or some other pill through his hair and other whacked out behavior.
I don’t remember if one exaggerated the other or if he was just pretty gone to begin with.
From what I understand, you’re correct. LSD was the main culprit, along with tranquilizers.
Some speculate that he also had schizophrenia but I don’t know if that was true. Sad,