- Evidence of other psychiatric/neurologic disorders sufficient to be the primary source of cognitive impairment (i.e., stroke, idiopathic Parkinson's disease, schizophrenia, bipolar or unipolar depression, seizure disorder, head injury with loss of consciousness within the past year) or a modified Hachinski's ischemia score of 5 or greater; delusions, hallucinations or depression not successfully treated or not on stable medical therapy for these conditions 30 days prior to enrollment; known or suspected history (within the past 10 years) of alcoholism or drug misuse