Objectives: This cross-sectional study investigated the relationships between behavioural and psychological symptoms of dementia (BPSD).
Methods: We recruited 194 patients with dementia from the memory clinic practice of six European Alzheimer's Disease Consortium centres. BPSD were assessed using a pre-designed questionnaire comprising the Neuropsychiatric Inventory (NPI). BPSD scores were analysed by Spearman's correlation analysis and principal components factor analysis. Results were confirmed by performing Varimax rotation of the factors.
Results: The NPI symptoms occurred very frequently: 96% of the patients displayed at least one symptom. Among them, apathy (59.6%) and depression (58.5%) were the most common abnormalities, followed by irritability (44.6%), anxiety (44%) and agitation (41.5%). Four NPI-based factors were identified (58% of the common variance): psychosis factor (irritability, agitation, hallucinations and anxiety), psychomotor factor (aberrant motor behaviour and delusions), mood liability factor (disinhibition, elation and depression) and instinctual factor (appetite disturbance, sleep disturbance and apathy).
Conclusion: Psychosis, psychomotor factor, mood liability factor and instinctual factor form four distinct behavioural syndromes in dementia. We report the novel observation that depression clusters together with disinhibition and elation within a mood liability factor. This finding highlights the nature of mood, and mood oscillations, from depression to disinhibition within the cluster, and has implications for treatment by taking into consideration the poles of the mood scale and any oscillation between them.