Paul Morphy suffered from certain psychological problems. These problems manifested themselves in various ways but none were severe enough to incapacitate him. Even up to his death at age 47, he associated with family and friends discussing literature, philosophy and theology. He followed chess, though apparently didn't play much in the last half-dozen years. He attended the opera as well as his mother's musical soirees and he attended serices at the St. Louis Cathedral daily.
Strangers found him quite peculiar in both his dress and his mannerisms. He shied away from the public and kept to himself. One of his closer friends noted that Morphy in his later life was generally happy, though morose at times.
see Morphy Madness
I don't think he ever approached insanity, but he certainly had his problems.
I've heard this somewhere but I've never known it to be true. I knew he died rather young, but that's all I know.