Preventative Semaglutide and Tirzepatide Fail to Alter Alzheimer's Progression in 5xFAD Mice

Growing evidence links metabolic dysfunction to the pathogenesis of Alzheimer's disease (AD), a devastating neurodegenerative condition with no cure. Current therapeutic strategies for AD are largely symptomatic, failing to halt or reverse disease progression. Gut-derived incretin hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), and their long-acting mimetics, have shown promise as potential disease-modifying therapies due to their metabolic and neuroprotective properties. This study investigates whether these incretin receptor agonists can prevent AD progression, addressing a critical gap in understanding their direct neurotherapeutic potential.

Researchers evaluated the preventative efficacy of semaglutide (a GLP-1R agonist) and tirzepatide (a GLP-1R/GIPR co-agonist) in the 5xFAD mouse model of Alzheimer's disease. Mice were treated for either 2 or 4 months, initiating treatment before overt pathology. Primary endpoints included memory and learning tasks, assessment of amyloid-β plaque deposition, and glial cell activation. Additionally, a non-amyloidogenic model was used, where mice received 3 days of incretin pre-treatment before lipopolysaccharide (LPS) administration to assess microglial activation and inflammatory marker expression.

Both semaglutide and tirzepatide treatments successfully lowered body weight and improved glucose tolerance in the 5xFAD mice, confirming their expected metabolic effects. However, despite these metabolic improvements and prolonged administration, neither compound produced measurable effects on cognitive function. Specifically, memory or learning tasks showed no significant differences between treated and control groups. Furthermore, direct neuropathological markers remained unchanged: amyloid-β plaque deposition was not reduced, and glial cell activation was not altered.

In the non-amyloidogenic model, 3 days of incretin pre-treatment also failed to modify microglial activation or the expression of inflammatory markers following LPS administration. These findings indicate a lack of direct neuroprotective or disease-modifying effects on AD pathology in these specific mouse models.