# Do GLP-1 Drugs Protect Against Dementia? A Predictor Moved | This GLP A post hoc SELECT analysis found semaglutide reduced increases in a proteomic dementia risk score, odds ratio 0.74 at five years and 0.91 at twenty. Publisher: This GLP Editorial Team Canonical: https://thisglp.com/research/do-glp1-drugs-protect-against-dementia Updated: 2026-09-18 Published: 2026-09-16 [← Research](https://thisglp.com/research) Evidence # Do GLP-1 Drugs Protect Against Dementia? A Predictor Moved Semaglutide slowed the rise of a 25-protein dementia risk score in SELECT participants. Nobody in the analysis developed dementia, or avoided it. [This GLP Editorial Team](https://thisglp.com/about)September 20267 min readUpdated September 2026 Effect on a predicted dementia score — not on dementia · 1.0 · 5-year signature · 26.0% lower predicted rate · 20-year signature · 8.8% lower · The score rose in both arms. It rose less on the drug. **Research, not medical advice.** This GLP is independent and educational. Nothing here is a substitute for individualized care from a licensed clinician, and reading it creates no doctor–patient relationship. Talk to your own provider before starting, stopping, or changing any medication, peptide, or therapy. See our [methodology](https://thisglp.com/methodology) and [terms](https://thisglp.com/terms). ## Key takeaways - A post hoc analysis of the SELECT trial in 2,970 adults aged 65 and over, semaglutide 2.4 mg against placebo. - The outcome is a validated 25-protein blood score that predicts dementia at 5 and 20 years. - Predicted risk rose in both groups. It rose less on semaglutide. - On the 5-year signature, odds ratio 0.74, 95% CI 0.65 to 0.85 — a 26.0% lower predicted event rate. - On the 20-year signature, odds ratio 0.91, 95% CI 0.88 to 0.94 — 8.8% lower. Nobody has measured that, and what has been measured is a predictor of it — a different thing, and worth keeping separate from the question people are actually asking. In a post hoc analysis of SELECT covering 2,970 adults aged 65 and over, a validated 25-protein blood score that forecasts dementia rose in both arms. It rose less on semaglutide, at an odds ratio of 0.74 on the five-year signature and 0.91 on the twenty-year one. A predictor moving is not the same as a disease not happening, and the gap between those two sentences is the whole of this page. One study that looked at cognitive impairment itself found 33 cases on oral semaglutide against 73 on a comparator in 246 elderly outpatients, a reduction its regression put at 77% with no confidence interval published[\[2\]](https://thisglp.com/research/do-glp1-drugs-protect-against-dementia#ref-2). A larger study of the same drug against another DPP-4 inhibitor found nothing, which is why [those two results have to be read together](https://thisglp.com/research/oral-semaglutide-cognitive-impairment). Nobody in this analysis developed dementia, and nobody avoided it. What was measured is a blood score built to predict it, and the distance between moving a predictor and moving an outcome is the same distance [a biological clock](https://thisglp.com/research/do-glp1-drugs-slow-aging) sits at from a lifespan. ## What was measured Serum samples taken at baseline and at week 104 from 2,970 SELECT participants aged 65 and over with overweight or obesity and cardiovascular disease but no diabetes. [\[1\]](https://thisglp.com/research/do-glp1-drugs-protect-against-dementia#ref-1) Those samples were run through a validated test that reads 25 proteins and returns a predicted risk of all-cause dementia over five and twenty years. This is a post hoc analysis. SELECT was designed to test whether semaglutide prevents cardiovascular events — a composite endpoint with [its own reading problems](https://thisglp.com/research/tirzepatide-heart-failure-composite) — not to answer anything about cognition, and the proteomic question was asked of its samples afterwards. ## Rate, not level Predicted dementia risk went up in both arms over the two years, which is what happens to a risk score as a cohort of 65-year-olds gets older. It went up less on semaglutide: 2.5-fold less on the five-year signature and 1.67-fold less on the twenty-year one. That is the paper’s own framing — reduced increases — and it is worth keeping, because “reduced dementia risk” describes something that did not happen here in two separate ways. The two horizons do not agree The five-year score moved substantially, odds ratio 0.74 with an interval of 0.65 to 0.85. The twenty-year score moved much less, 0.91 with an interval of 0.88 to 0.94 — a tight interval around a small effect. A signature built to read further ahead responded least. That is either a real statement about a short-term effect on a long-term process, or a sign that a two-year window moves the near-term proteins more readily than the ones carrying the distant signal. The analysis cannot tell you which. ## What a validated score validates That people with higher scores develop dementia more often than people with lower ones. That is what validation of a predictive test establishes, and it is a fact about the population the test was built on. It does not establish that lowering somebody’s score lowers their risk. A marker can track a disease faithfully and still be a passenger rather than a driver. In which case moving it changes the reading and not the future — the reason [the markers easiest to move](https://thisglp.com/research/glp1-pcos-insulin-resistance) are usually the ones proving least. ## Cognitive signs in a clinic record A US health-record cohort asked a closer question in a different group: 13,007 adults with a psychiatric diagnosis, 1,261 of whom started semaglutide [\[3\]](https://thisglp.com/research/do-glp1-drugs-protect-against-dementia#ref-3). The outcome was a 0-to-100 score built from what clinicians wrote down in routine cognitive assessments of memory, attention and orientation, over the 12 months after a diabetes drug was started. Scores averaged 11.14 on semaglutide against 14.91 with no treatment, 13.46 on glipizide and 13.69 on empagliflozin. Against sitagliptin, at 12.52, the gap was not significant. Effect sizes were similar across diagnoses but consistently significant only in major depression. The authors say randomized trials are needed to show the drug caused it, which is the same limit [a score made of clinical notes](https://thisglp.com/research/semaglutide-and-recorded-cognitive-signs) carries on its own. ## What would settle it A trial with dementia as its endpoint, in people followed long enough to get it. That is expensive, slow, and the reason proteomic signatures are attractive in the first place. Until one exists, this is a promising result about a score. The trial it came from was asking about hearts, reported honestly by authors who say their drug slowed the progression of a signature rather than of a disease — which is more care than [most conclusions take](https://thisglp.com/research/do-glp1-drugs-help-parkinsons-disease). ## Frequently asked Does semaglutide reduce dementia risk? This analysis measured a blood score that predicts dementia, not dementia itself. Nobody in it developed or avoided the disease. What does 'reduced increases' mean? Predicted risk rose in both groups over two years, as it does with age. It rose less on semaglutide — 2.5-fold less on the five-year signature. Why do the five and twenty-year results differ? The five-year score moved substantially, odds ratio 0.74, and the twenty-year one much less, 0.91. A signature built to read further ahead responded least, and the analysis cannot explain why. Does semaglutide help memory in people with depression or other psychiatric conditions? In a US health-record cohort of 13,007 adults with a psychiatric diagnosis, clinician-recorded cognitive signs scored 11.14 on semaglutide against 14.91 with no treatment. The association was consistently significant only in major depression, and it was not a randomized trial. Was the trial designed for this? No. SELECT tested whether semaglutide prevents cardiovascular events. This question was asked of its stored samples afterwards. ## Sources 1. \[1\] Jiménez-Mausbach M, et al. (2026). Semaglutide attenuates a proteomics-based dementia risk signature in older adults with overweight or obesity and cardiovascular disease without diabetes: A post hoc analysis of the SELECT phase 3 trial Alzheimer's & Dementia. [PMID 42571323](https://pubmed.ncbi.nlm.nih.gov/42571323/) 2. \[2\] Armentaro G, et al. (2026). Oral semaglutide vs DPP-4 inhibitors in reducing risk of cognitive impairment in elderly patients with HFpEF and obesity Internal and Emergency Medicine. [PMID 42622752](https://pubmed.ncbi.nlm.nih.gov/42622752/) 3. \[3\] De Giorgi R, et al. (2026). Cognitive signs and symptoms in people with a psychiatric diagnosis on semaglutide: a retrospective cohort study of 13 007 patients in the USA BMJ Mental Health. [PMID 42624612](https://pubmed.ncbi.nlm.nih.gov/42624612/) ## Where to get it ### Best GLP-1 injections Every injectable seller we can verify, with the price each one publishes and an honest read of what the trials measured. 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