Psychiatric symptoms in cases of clinically diagnosed Alzheimer's disease.

All incident cases of clinically diagnosed Alzheimer's disease were identified through the unique record linkage system of the Mayo Clinic. Thirty-nine (32%) of the sample of 122 had a psychiatric history that preceded the onset of CDAD by at least 3 years. Twenty-five percent of the study population had had an episode of delirium within 2 years of the onset of CDAD. Eighty-four percent of the cases had psychiatric symptoms in the course of CDAD that were documented in their medical records. Specific symptom patterns included agitation, combativeness, confusion and disorientation, depression, psychosis, and wandering. These symptoms occurred more frequently in clusters than singularly.