For decades, medicine has treated memory loss, brain fog, and neurodegenerative disease as inevitable — but what if the real battle is happening at the cellular level, inside your brain's own immune system? In this episode, six-time New York Times bestselling author and neurologist Dr. David Perlmutter joins Dr. Amen & Tana to unpack the findings from his groundbreaking new book, Brain Defenders. We explore microglia — the brain's immune cells that can act as either warriors of protection or agents of destruction, depending on how we live. Dr. Perlmutter breaks down the overlooked role of inflammation in conditions ranging from dementia to long COVID and lays out practical, evidence-based strategies to counter threats such as poor diet, environmental toxins, and lack of restorative sleep. If you've ever wondered whether cognitive decline is truly inevitable — or whether you have more control over your brain's future than you think — this conversation will change how you think about aging, disease, and prevention.