The prevalence of neuropsychiatric symptoms in Alzheimer's disease: Systematic review and meta-analysis

Background: Neuropsychiatric symptoms (NPS) are being increasingly recognized as common serious problems in Alzheimer's disease (AD). However, published data on the prevalence of NPS in persons with AD are conflicting. This meta-analysis aimed to estimate the prevalence of NPS in persons with AD.

Methods: Studies published from 1964 to September 30, 2014, were identified from PubMed and Embase database, reference lists and conference abstracts. We calculated prevalence rates and conducted meta-regression analysis with random-effects model, according to study characteristics, population demographics or condition information.

Results: We identified 48 eligible articles, which provided data for 12 NPS reported in Neuropsychiatric Inventory (NPI). The most frequent NPS was apathy, with an overall prevalence of 49% (95% CI 41-57%), followed by depression, aggression, anxiety and sleep disorder, the pooled prevalence estimates of which were 42% (95% CI 37-46%), 40% (95% CI 33-46%), 39% (95% CI 32-46%) and 39% (95% CI 30-47%), respectively. The less prevalent NPS were irritability (36%, 31-41%), appetite disorder (34%, 27-41%), aberrant motor behavior (32%, 25-38%), delusion (31%, 27-35%), disinhibition (17%, 12-21%) and hallucination (16%, 13-18%). Least common was euphoria, with an overall prevalence of 7% (95% CI 5-9%).

Limitations: Several aspects, such as the quality of included studies were not always optimal and there was significant heterogeneity of prevalence estimate across studies.

Conclusions: NPS were observed to be highly prevalent in AD patients. Disease duration, age, education level, population origin and the severity of cognitive impairment had influence on the prevalence of some NPS.