The virus-like structure of a brain protein may explain cancer-induced memory loss. In some cancer patients, the immune system reacts to tumors by producing antibodies against a protein called Arc. This protein plays a crucial role in memory formation. The antibodies generated resemble a virus and can cross the blood-brain barrier, impacting Arc’s function in the brain. This disruption may contribute to cognitive deficits, affecting memory and learning. Understanding this mechanism sheds light on the intricate relationship between the immune response to cancer and cognitive function, providing insights for potential interventions to alleviate cancer-induced memory issues.