Behavioral and Psychological Signs and Symptoms of Dementia (BPSD) are important manifestations of Alzheimer's Disease (AD) and other forms of dementia, because they are associated with care-giver distress, increase the likelihood of institutionalization, and may be associated with more rapid cognitive declineIn this study (REAL.FR for Réseau sur la maladie d'Alzheimer Français) we prospectively used the Neuropsychiatric Inventory NPI to examine BPSD. 255 AD patients with a Mini-Mental State Examination (MMSE) score between 11 and 20 and 244 AD patients with a MMSE between 21 and 30 were examined. Factor analysis was cerried out leading to three different syndromes according to the level of cognitive impairment.BPSD were detected in 92.5 % of the patients with a MMSE between 11 and 20, and in 84 % of the patients with a MMSE between 21 and 30. Apathy was the most common abnormality, followed by anxiety and dysphoria.These results in a French cohort of patients with AD underline the importance of the evaluation and finallv of the treatment of BPSD.