The description for the Nothic in the 5e Monster Manual contains the following text:
Rather than gaining the godlike supremacy they crave, some wizards who devote their lives to unearthing arcane secrets are reduced to creeping, tormented monsters by a dark curse left behind by Vecna, a powerful lich who, in some worlds, has transcended his undead existence to become a god of secrets. Nothics retain no awareness of their former selves, skulking amid the shadows and haunting places rich in magical knowledge, drawn by memories and impulses they can't quite understand.
Is there any further detail elsewhere? Is this something that just happens? Could a wizard (or other spellcaster) in my game just wake up one morning a Nothic for no reason? Or are there other variables involved?
If it helps to answer the question, what is Vecna's curse? Are there any related publications that entail it?