Neuropsychiatric symptoms and functional status in Alzheimer's disease and vascular dementia patients

Neuropsychiatric symptoms (NPS) are increasingly recognized as common in patients with dementia, both of degenerative (Alzheimer's disease, AD) or vascular origin (vascular dementia, VaD). In this study, 302 demented patients, 166 with AD and 136 with VaD, were evaluated for NPS according to the Neuropsychiatric Inventory (NPI) score at the Alzheimer's Evaluation Unit of Casa Sollievo della Sofferenza Hospital-IRCCS, San Giovanni Rotondo, Italy. A comprehensive geriatric assessment was also performed in all demented patients. The means of NPI scores did not differ in two groups. The overall prevalence of NPS was similar in both groups of patients (69.7% vs. 69.4%). Patients with AD had higher frequency in agitation/aggression and irritability/lability than VaD patients. Logistic analysis demonstrated a significant association between severity of the cognitive impairment and depression and eating disorders in both AD and VaD patients. The association with agitation/aggression, irritability/lability, and aberrant motor activity was found in AD only, and with apathy in VaD patients only. In both AD and VaD patients, there was a significant association between the impairment in activities of daily living (ADL) and the majority of NPI domains. A significant association was also found between the impairment of the instrumental activities of daily living (IADL) and agitation/aggression, anxiety, aberrant motor activity in AD and depression, apathy, irritability/lability, sleep disturbance and eating disorders in both AD and VaD patients. In particular, a causal mediation analysis was performed to better understand whether the relationship of NPS to functional impairment was direct or mediated by severity of cognitive dysfunction, i.e., Clinical dementia rating scale (CDR) score. Only agitation/aggression was mediated by the CDR score in affecting ADL status in VaD patients (OR: 1.12, 95% CI: 1.01-1.27). The NPI-Distress scores showed a significantly higher levels of distress in caregivers of AD than VaD. There were significant differences between AD and VaD patients with NPS, and these symptoms varied according to dementia subtype and severity and induced marked disability in ADL and IADL, increasing, prevalently, the distress of the caregivers of AD patients.