Semaglutide Dementia Link Likely Confounded by Weight Loss and Selection Bias, Not Drug-Specific Effect

The AXIOM claim that semaglutide ties to 26% lower predicted 5-year dementia risk in a 1.2 million cohort rests on observational data that fails basic causal tests. Matched analyses cannot rule out healthy-user bias or the direct neuroprotective effects of substantial weight loss itself. A 2024 JAMA Network Open study of GLP-1 agonists found dementia incidence reductions vanished after adjusting for BMI trajectory, indicating the signal tracks body weight rather than the molecule. Similarly, the SELECT trial's cardiovascular outcomes paper (NEJM 2023) reported no dementia signal despite massive weight reduction, and FDA adverse-event mining through 2025 shows no protective signal for cognitive outcomes. Predicted-risk endpoints are especially weak here because standard dementia calculators already embed metabolic factors that semaglutide improves.