Results from the ELAD (Evaluating Liraglutide in Alzheimer's Disease) trial, published in Nature Medicine in 2025, provide the first Phase IIb evidence that a GLP-1 receptor agonist can slow neurodegeneration in Alzheimer's disease. The multicenter, randomized, double-blind, placebo-controlled study enrolled 204 non-diabetic patients with mild-to-moderate Alzheimer's across 24 clinics in the United Kingdom (ClinicalTrials.gov: NCT01843075).

Trial Design

Participants were randomized 1:1 to receive either daily subcutaneous liraglutide (titrated up to 1.8 mg) or placebo for 52 weeks. The primary endpoint was change in cerebral glucose metabolic rate measured by FDG-PET imaging. Secondary endpoints included brain volume changes assessed by MRI volumetric analysis and cognitive function measured by composite scoring.

Results

The study did not meet its primary endpoint. There was no statistically significant difference in cerebral glucose metabolic rate between the liraglutide and placebo groups (difference = -0.17; 95% CI: -0.39 to 0.06; P = 0.14).

However, secondary outcomes showed notable findings. MRI volumetric analysis and voxel-based morphometry revealed that liraglutide-treated patients experienced approximately 50% less brain volume loss compared to placebo, with protective effects observed in the frontal, temporal, and parietal lobes as well as total gray matter. Cognitive assessment using the ADAS-Exec composite score (measuring memory, comprehension, language, and spatial orientation across 18 tests) showed a statistically significant benefit in the treatment group (0.15; 95% CI: 0.03-0.28; P = 0.01), reflecting approximately 18% slower cognitive decline over 12 months.

The treatment was well tolerated in non-diabetic Alzheimer's patients. The most common adverse event was gastrointestinal symptoms (25.5% of the liraglutide group). Serious adverse events occurred less frequently in the liraglutide group (6.9%) compared to placebo (17.6%).

Proposed Mechanisms

The researchers note that GLP-1 receptor agonists may exert neuroprotective effects through multiple pathways: reducing neuroinflammation, lowering insulin resistance in the brain, decreasing the toxic effects of amyloid-beta and tau proteins, and normalizing synaptic plasticity. A limitation is that liraglutide has minimal blood-brain barrier penetration (Kp < 0.00031), though it may access the central nervous system via circumventricular organs or subarachnoid vasculature.

Implications for GLP-1 Research

These findings have prompted larger investigations. Novo Nordisk is currently conducting two Phase III trials (EVOKE and EVOKE Plus, NCT04777396 and NCT04777409) evaluating oral semaglutide 14 mg daily in 3,680 patients with early Alzheimer's disease, with results expected in 2025-2026. These trials use the CDR-SoB (Clinical Dementia Rating Sum of Boxes) as the primary endpoint and require amyloid-positive participants ages 55-85.

The results were first presented at the Alzheimer's Association International Conference (AAIC) in July 2024. The full study is available at Nature Medicine (PubMed ID: 41326666).