The song's name, "Manic Depression," is an old name for bipolar disorder, a mental health disorder. There is no evidence the Hendrix ever suffered from bipolar disorder himself. Hendrix was doing a press conference in London and his manager at the time, Chas Chandler, told him that he sounded like a manic depressive. So the next day Hendrix wrote this tune.
Avi - Ashdod, Israel