Grouping and trajectories of the neuropsychiatric symptoms in patients with Alzheimer's disease, part I: symptom clusters.

Behavioral and psychological symptoms of dementia (BPSD) are frequently observed in Alzheimer's disease (AD) and affect more than 80% of patients over the course of AD. The goal of this study was to establish a model for grouping the symptoms of BPSD into clinical syndromes. Over a 24-month period, an observational study was conducted using a population of ambulatory patients with AD of mild to moderate severity. The Neuropsychiatric Inventory (NPI) was administered to the patients' caregivers every 6 months. BPSD were grouped using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) of the NPI scores of each assessment. The sample population consisted of 491 patients (70.9% women) with an average age of 75.2 years (SD=6.6). The five EFA suggested that there was a stable three-factor structure. According to the results of the EFA, three models of symptom grouping were adjusted using CFA methodology. The CFA model that satisfactorily grouped the NPI scores into three factors included a psychotic syndrome (hallucinations, delusions), an affective syndrome (depression, anxiety, irritability, agitation) and a behavior syndrome (euphoria, disinhibition, apathy, aberrant motor behavior). Based on our findings, we propose a model for grouping the BDSD in which there are core nuclear syndromes (psychotic and affective) as well as an unspecified behavior syndrome comprising satellite symptoms that may be related to the presence of the nuclear syndromes.