Phenomenology and clinical correlates of delusions in Alzheimer disease.

OBJECTIVES: The objectives of this study were to determine whether anosognosia, depression, and elevated mood are associated with delusions in Alzheimer disease (AD), and to examine the validity of standardized diagnostic criteria for psychosis of dementia.
METHOD: The authors assessed a consecutive series of 771 patients with AD attending a dementia clinic with a comprehensive neuropsychologic and psychiatric evaluation that included specific measures of delusions, hallucinations, anosognosia, depression, and elevated mood.
RESULTS: Delusions were found in one-third of the patients and hallucinations in 7%. Most patients with hallucinations also had delusions. A principal component analysis of the Psychosis Dementia Scale, which rates the presence and severity of delusions, produced the factors of paranoid misidentification and expansive delusions. Paranoid, but not expansive, delusions increased across the stages of the illness. Anosognosia and depression were significantly and independently associated with the presence of delusions, whereas elevated mood was significantly associated with expansive, but not paranoid, delusions. A multiple logistic regression analysis demonstrated that delusions in AD were significantly associated with depression, anosognosia, overt aggression, and agitation.
CONCLUSIONS: Anosognosia, depression, global cognitive deficits, and elevated mood are the main psychiatric correlates of paranoid misidentification and expansive delusions in AD, whereas overt aggression and agitation are the most frequent behavioral concomitants of psychosis in AD.