Whey protein and its hydrolysates are ubiquitously applied in the food system. However, their effect on cognitive impairment remains unclear. This study aimed to investigate the potential ability of whey protein hydrolysate (WPH) to ameliorate cognitive degeneration. WPH intervention in Crl:CD1 (ICR, Institute for cancer research) mice and aged C57BL/6J mice in a scopolamine-induced cognitive impairment model for 10 days were evaluated. Behavioral tests indicated that WPH intervention improved the cognitive abilities in ICR and aged C57BL/6J mice (p < 0.05). Scopolamine enhanced the Aβ_1-42 level in the brain tissue, and the WPH intervention exhibited a similar therapeutic effect to donepezil in ICR mice. A noticeable reduction occurred in serum Aβ_1-42 level of aged mice treated with WPH. The histopathological study of the hippocampus showed that WPH intervention alleviates neuronal damage. Hippocampus proteomic analysis suggested possible mechanisms of WPH action. The relative abundance of Christensenellaceae, a gut microbe related to Alzheimer’s disease, was altered by WPH intervention. This study demonstrated that short-term WPH intake protected against memory impairment induced by scopolamine and aging.

Background: Response speed refers to an individual’s ability to perceive and react to harmful stimuli, which can vary due to genetics, neural regulation, and environmental factors. Our previous study demonstrated that whey protein hydrolysate was a potential means to enhance cognitive function. Methods: This study used a variety of behavioral methods to evaluate the functional effects of whey protein hydrolysate on improving reaction speed, and revealed its potential mechanisms through proteomics analysis. Results: The results showed that whey protein hydrolysate improved response speed in mice when tested against thermal pain, mechanical strength stimuli, and prepulse inhibition. Proteomic analysis of the hippocampus revealed changes in proteins related to arginine and proline metabolism, as well as neuroactive ligand–receptor interactions. Conclusions: These findings provide new insights into the neuromodulatory effects of whey protein hydrolysate and support its potential role in enhancing response speed and cognitive performance.