Why does ketamine provide miraculous relief for some people with severe depression but leave others behind? This episode unpacks a groundbreaking study that points to a surprising answer: hidden inflammation. Join us as we explore a pioneering 2025 paper that uses a novel method called Intron Retention (IR) to re-examine the biology of ketamine treatment. Researchers discovered that, even before treatment, those who don't respond to ketamine often show signs of a highly active immune system, as if their body is fighting a persistent viral infection. Here's the stunning twist: the study reveals that ketamine has a powerful anti-inflammatory effect in everyone—even in so-called "non-responders." This challenges everything we thought we knew about treatment resistance. It suggests that for these individuals, ketamine isn't ineffective, but rather insufficient to overcome the massive underlying inflammatory burden. This paradigm shift reframes "non-response" not as a failure, but as a signpost pointing toward a future of personalized medicine. Could combining ketamine with targeted anti-inflammatory or antiviral therapies unlock its potential for millions more? Listen now to understand the science that could revolutionize mental health care.