It occurs to me, that while “madness” still exists today, the psychological conditions of times past have changed.
In the modern world we have more frames of reference and extreme behavior normalizes from the cloister of isolation.
Watching old movies from the 50s for instance reveals this phenomena, that even ordinary people developed prattling around in their own minds in ways somehow different than modern awareness allows.
Not to diminish the seriousness of “mood disorders”, I can only think that once upon a time being an intellectually and emotionally isolated genius would be harder on one’s development than the exposure granted in today’s world.