Alpha-Lipoic Acid and Metformin Combination Therapy Synergistically Activate Nrf2-AMPK Signaling Pathways to Ameliorate Cognitive Dysfunction in Type 2 Diabetic Encephalopathy: A Preclinical Study

Diabetic encephalopathy affects over 40% of diabetic patients globally, yet effective treatments remain critically limited. This study investigated the synergistic neuroprotective potential of alpha-lipoic acid (ALA) and metformin through the coordinated activation of Nrf2 and AMPK signaling pathways in type 2 diabetes mellitus (T2DM)-induced encephalopathy. Using a clinically relevant streptozotocin-nicotinamide-induced T2DM rat model, sixty male Sprague-Dawley rats were randomly assigned to five groups: control, diabetic, ALA-treated (300 mg/kg), metformin-treated (50 mg/kg), and combination-treated groups over eight weeks. Combination therapy produced statistically validated synergistic effects with significant interaction terms (p < 0.01) across all evaluated parameters. Nuclear Nrf2 translocation increased 3.9-fold and AMPK phosphorylation rose 3.2-fold compared to monotherapies, surpassing mathematical additivity. Mitochondrial function was remarkably restored, with ATP production increasing to 92% of control levels. Cognitive performance was normalized, with spatial memory approaching control values. Combination index analysis (CI < 1.0) confirmed true synergistic interactions across molecular, cellular, and behavioral endpoints. These findings establish a novel convergent mechanism providing compelling evidence for combination ALA-metformin therapy as an innovative treatment strategy for diabetes-associated neurodegeneration.