PSYCHOMETRIC AND SPECT STUDIES IN ALZHEIMERS-DISEASE WITH AND WITHOUT DELUSIONS

Delusions are common in Alzheimer's disease (AD), but their pathophysiological basis is poorly understood. Fifteen patients meeting NINCDS-ADRDA criteria for probable AD were studied with psychometric assessment and brain-dedicated SPECT (xenon-133 and HMPAO). None of the subjects had delusions at the start of the study. One year later, psychometric testing and SPECT were repeated. Three patients had developed Capgras syndrome, and three others had developed non-Capgras delusional disorders in the interval. Psychometric and rCBF measures at baseline and at one year were compared. At baseline rCBF was significantly higher in the right temporal regions in the patients who developed delusions (p < 0.05). One year later, rCBF in the right temporal regions had declined in the psychotic patients. AD patients who developed delusions showed deterioration in right anterior temporal rCBF compared to AD without delusions. In the setting of AD, right temporal function deterioration may contribute to the development of delusions.