not anymore, he doesn't...lol
On a more serious note, so many centuries after his death, it really would be impossible to definitively answer this, but it doesn't seem very likely at all. Manic depressives (now known as sufferers of bipolar disorder) are not known for their reserve, especially during a manic phase. He did have friends, (lots of letters to prove it), but it's not like Newton was a party animal. When one gets into one's work, shutting out the rest of the world isn't so strange. And being that he was so far ahead of his time, how many people would he have to just talk (then) cutting edge physics with?
He did have the symptoms of mercury poisoning toward the end of his life, which makes some sense, since he was an alchemist as well and mercury was common in that art, being they didn't know the danger yet. That could definitely contribute to the impression of possible insanity, since mercury poisoning affects the brain and CNS.
I doubt he'd have done so much and gotten so far if he suffered from any serious mental illness, so I'd say he didn't have manic depression...