WordNet (r) 3.0 (2006):

unhinged
    adj 1: affected with madness or insanity; "a man who had gone
           mad" [syn: brainsick, crazy, demented, disturbed,
           mad, sick, unbalanced, unhinged]

Moby Thesaurus II by Grady Ward, 1.0:

59 Moby Thesaurus words for "unhinged":
   abnormal, bereft of reason, brainsick, crackbrained, cracked,
   crazed, crazy, daft, deluded, demented, deprived of reason,
   deranged, disarranged, disjointed, dislocated, disoriented,
   displaced, distraught, flighty, hallucinated, insane, irrational,
   loco, lunatic, mad, maddened, manic, mazed, mental,
   mentally deficient, meshuggah, moon-struck, non compos,
   non compos mentis, not all there, not right, odd, of unsound mind,
   off, out, out of gear, out of joint, psycho, queer, reasonless,
   senseless, sick, stark-mad, stark-staring mad, strange, tetched,
   touched, unbalanced, unjointed, unsane, unsettled, unsound,
   wandering, witless