It depends also on the class:
Delusional: +70 attack power (Rogue, Hunter, Paladin, Warrior, Druid)
Dimentia: "Down the rabbit hole..." Every 5 seconds either gives you +5% or -5% damage/healing. (Druid, Shaman, Priest, Warlock, Mage, Paladin)
Kleptomania: +35 agility (Warrior, Rogue, Paladin, Hunter, Druid)
Manic: +35 haste (spell, melee and ranged) (All classes)
Martyr Complex: +35 stamina (All classes)
Meglomania: +41 damage/healing (Druid, Shaman, Priest, Warlock, Mage, Paladin)
Narcissism: +35 intellect (Druid, Shaman, Priest, Warlock, Mage, Paladin, Hunter)
Paranoia: +35 spell/melee/ranged crit strike rating (All classes)
Sociopath: +35 strength (Paladin, Rogue, Druid, Warrior)
The buff lasts for 30 sec.