Comparison of Cognitive Intervention Strategies for Individuals With Alzheimer's Disease: A Systematic Review and Network Meta-analysis

Accumulating evidence has shown the effectiveness of cognitive interventions, which can be divided into cognitive training (CT), cognitive stimulation (CS), cognitive rehabilitation (CR), and combined interventions (i.e., cognitive interventions combined with other non-pharmacological interventions such as physical exercise), in individuals with Alzheimer's disease (AD). However, the effectiveness of cognitive interventions varies greatly among studies and more comprehensive studies are required. We aimed to evaluate whether the current evidence shows that cognitive interventions are effective at improving cognition, neuropsychiatric symptoms, depression, quality of life, and basic activities of daily living among individuals with possible or probable AD. Randomized controlled trials of all types of cognitive intervention were identified for inclusion in pairwise and network meta-analyses. There was a moderate and statistically significant post-intervention improvement in global cognition among individuals with AD for all types of cognitive intervention compared to control interventions (39 studies, g = 0.43, 95% CI: 0.28 to 0.58, p < 0.01; Q = 102.27, df = 38, p < 0.01; I² = 61.97%, τ² = 0.13). Regarding the specific types of cognitive intervention, combined interventions had the highest surface under the cumulative ranking curve (SUCRA) value (90.7%), followed by CT (67.8%), CS (53.4%), and lastly CR (28.9%). Significant effects of cognitive interventions were also found for working memory, verbal memory, verbal fluency, confrontation naming, attention, neuropsychiatric symptoms, basic activities of daily living, and quality of life.