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Objective: Although the Global Deterioration Scale has been widely used since its publication in 1 982, its stages are based on implicit assumptions about the linearity, temporality, and interdependence of cognitive, functional, and behavioral impairment in Alzheimer’s disease. The authors evaluated the validity of these assumptions and tested the hypothesis that psychopathology and functional impairment would occur in earlier stages than the Global Deterioration Scale predicts. Method: The analyses were based on data on 324 patients with Alzheimer’s disease who were selected from a registry ofsuch patients. Data analyses included 1) descriptive statistics on the frequency ofpsychiatric symptoms and difficulties with activities of daily living and 2) logistic regression, with symptoms and functional impairment as independent variables, to testforsignificant changes in patients ’ status between stages ofthe Global Deterioration Scale. Results: More than 50 % of the patients at stage 2 displayed psychopathology, and 32 % had two or more symptoms. The significant increase in psychiatric symptoms occurred between stages 3 and 4, not between stages 5 and 6 as predicted by the Global Deterioration Scale. Impairment in functionalstatus was observed at allstages, and significant increases occurred between stages 3 and 4 as well as between stages 5 and 6. Conclusions: