- Patients with vitamin B12 deficiency, abnormal thyroid function, or personal history of either any clinically defined medical disorder or any clinically defined neurological/psychiatric disorder (other than AD), including (but not limited to):, stroke, brain lesions, , cerebrovascular condition, other neurodegenerative disease, significant head trauma (loss of consciousness greater than half an hour, or related anterograde amnesia), multiple sclerosis; or personal history of previous neurosurgery or brain radiation