Cordyceps (Cordyceps militaris) and its key compound cordycepin dramatically improved learning and memory in mice with induced cognitive decline. Over two weeks, mice given cordyceps extract (200 mg/kg/day) or cordycepin (10 mg/kg/day) performed far better on maze and recognition tests, showing stronger short-term and long-term memory. Both treatments also reduced oxidative stress in brain tissue, confirming cordyceps’ direct neuroprotective and cognition-enhancing effects.