[Main components of Neuropsychiatric Inventory in Alzheimer's disease. Definition of behavioral syndromes]

Behavioral disturbances are an important part of the clinical picture of Alzheimer's disease (AD). Behavior is usually assessed considering each symptom one by one. Few studies have tried a more comprehensive approach. We assessed behavior in AD patients in order to define patterns of behavioral disturbances, thereby improving its classification.

Ninety consecutive AD patients were evaluated from November 1997 to November 2000. All patients meet the NINCDS-ADRDA criteria for probable or possible AD. Patients with atypical clinical features were not included. Clinical evaluation included of the Neuropsychiatric Inventory ("chronic" scores), Mini-Mental State Examination, RDRS-2 and CDR. Statistical analysis was performed with factor analysis (SPSS).

Factor analysis rendered a three-factor solution. Each factor can be considered a behavioral syndrome: the psychotic syndrome (hallucinations and delusions), the affective syndrome (depression, euphoria and anxiety) and the discontrol syndrome (agitation, irritability and disinhibition). A relevant number of patients had mild behavioral disturbances, not meeting statistical criteria for the syndromes defined above.

Behavioral disturbances in AD can be classified into four groups or syndromes. Our results are in accordance with and expand the results of previous reports, using different behavior scales and statistical analysis. Future studies must be aimed at better characterizing the extensive group with mild behavioral disturbances, not sufficiently defined by the methods applied in the present and previous studies.