Liraglutide and Exenatide in Alzheimer's Disease and Mild Cognitive Impairment: A Systematic Review and Meta-Analysis of Cognitive Outcomes.

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) exhibit neuroprotective properties in preclinical models of Alzheimer's disease (AD), reducing amyloid accumulation, neuroinflammation, and insulin resistance within the brain. However, clinical evidence regarding their cognitive effects in AD and mild cognitive impairment (MCI) remains inconclusive. To evaluate the effects of GLP-1 RAs on cognitive outcomes in patients with AD or MCI due to AD. A systematic review was conducted according to PRISMA 2020 and registered in PROSPERO (CRD420251143171). Although the original registry was broad, the identification of a small set of homogeneous randomized controlled trials (RCTs) during screening, prior to data extraction, allowed for a random-effects meta-analysis of cognitive outcomes. RCTs enrolling adults with clinically or biomarker-confirmed AD or MCI were included. Interventions comprised liraglutide or exenatide compared with placebo. Standardized mean differences (SMD) in global cognitive scores were pooled using a random-effects model (restricted maximum likelihood [REML] estimator with Hartung-Knapp adjustment). Three randomized trials (n = 278 participants; 51% women; mean age 68 ± 7 years) met inclusion criteria. Treatment duration ranged from 26 weeks to 18 months. Pooled analysis revealed no significant effect of GLP-1 RAs on global cognition compared with placebo -0.21 (95% CI -0.81 to 0.38; I = 47%; τ = 3.77). Sensitivity analyses restricted to liraglutide or studies ≥ 12 months yielded similar results. Current randomized evidence does not support cognitive improvement with GLP-1 RAs in AD or MCI.