The relationship between psychiatric symptoms and regional cortical metabolism in Alzheimer's disease

Cognitive and noncognitive psychiatric symptoms were systematically evaluated in 21 patients with Alzheimer's disease by using the Neurobehavioral Rating Scale. Regional cerebral metabolic activity was measured in each patient by [18F]fluorodeoxyglucose PET. Significant correlations emerged between global cortical metabolic activity and the Agitation/Disinhibition factor score, Cognition factor score, and total score. Relationships between noncognitive symptoms and metabolic activity were regionally specific, with significant correlations between Agitation/Disinhibition factor score and metabolism in the frontal and temporal lobes, between Psychosis factor score and metabolism in the frontal lobe, and between Anxiety/Depression factor score and metabolism in the parietal lobe. These results suggest that psychiatric symptoms are fundamental expressions of the cortical dysfunction of Alzheimer's disease.