Depression is a serious mental health condition affecting over 300 million people worldwide, with many patients not responding well to standard antidepressants. This review examines both traditional antidepressants like SSRIs and exciting new treatments including ketamine and psilocybin, as well as brain stimulation techniques. The key finding is that different treatments work through similar mechanisms—all ultimately enhancing brain cell connections and reducing inflammation—suggesting that combining different approaches might work better than single therapies.