For 43 patients with probable Alzheimer's disease who were screened for
psychiatric disorders, the interrater reliability of the Global
Deterioration Scale, BPRS, and Hamilton Rating Scale for Depression was
high (intraclass correlation, 0.82-0.998). As expected, the prevalence of
psychiatric symptoms in this sample was low. The score on the Zung
Self-Rating Depression Scale correlated with the score on the rater-
administered Hamilton depression scale in patients whose Alzheimer's
disease was of low severity (N = 24) but not high severity (N = 19).