Combined Effects of Donepezil and Memantine on Behavioral and Psychological Symptoms, Cognitive Function, and Daily Living Abilities in Patients With Alzheimer's Disease.

Aims/Background Combined with memantine, donepezil has a beneficial impact on the treatment of moderate to severe Alzheimer's disease (AD), but it can potentially increase the risk of adverse events. The aim of this study is to compare the effects of low-dose and high-dose donepezil combined with memantine on the behavioral and psychological symptoms, cognitive function, and daily living abilities of patients with moderate to severe AD, and to explore their safety. Methods This retrospective study includes 106 AD patients who received treatment in the Third People's Hospital of Fuyang from January 2022 to January 2024. The patients were grouped according to treatment regimen: patients receiving low-dose donepezil (5 mg/day) combined with memantine were included in the low-dose group (n = 45), and those receiving high-dose donepezil (10 mg/day) combined with memantine were included in the high-dose group (n = 61). The assessment results of behavioral and psychological symptoms, cognitive function, daily living ability, quality of life, sleep quality, as well as the occurrence of adverse reactions during treatment were obtained from electronic medical records for the two groups of patients before and after 24 weeks of treatment, and were compared using appropriate statistical tests. Results After 24 weeks of treatment, the scores of neuropsychiatric inventory (NPI) and behavioral pathology in Alzheimer's disease rating scale (BEHAVE-AD) were similar between the two groups (p > 0.05). The scores of Mini-Mental State Examination (MMSE) and Alzheimer's disease assessment scale-cognitive section (ADAS-Cog) were similar between the two groups (p > 0.05). The scores of activities of daily living (ADL) were comparable between the two groups (p > 0.05), and the low-dose group had significantly higher quality of life-Alzheimer's disease (QOL-AD) scores compared to the high-dose group (p < 0.05). The Pittsburgh sleep quality index (PSQI) scores of patients in the high-dose group were significantly higher than those before treatment and those in the low-dose group (p < 0.05). There was no statistically significant difference in PSQI scores between the low-dose group before and after treatment (p > 0.05). During the treatment period, the total incidence of adverse reactions in the low-dose group was significantly lower than that in the high-dose group (11.11% vs. 27.87%, p < 0.05). Conclusion Both 5 mg/day or 10 mg/day donepezil in combination with memantine holds the potential to improve behavioral and psychological symptoms, cognitive function and daily living abilities in patients with moderate-to-severe AD. In addition, high doses of donepezil may lead to decreased sleep quality in patients, increased risk of adverse reactions, and less improvement in quality of life than low doses.