The podcast episodes provided focus extensively on defining and understanding major depressive disorder, its symptoms, and its impact. Episode "Why We Get Depressed with Heather Berlin" from the StarTalk Radio podcast discusses the neuroscience behind depression, including the role of neurotransmitters, hormones, and life experiences in this complex condition.

The "Psychotic Depression with Dr. Cummings" episode from the Psychiatry & Psychotherapy Podcast examines psychotic depression, a distinct form of major depressive disorder characterized by the presence of hallucinations and delusions. The episode emphasizes the importance of recognizing and addressing this underreported and often undertreated aspect of depression.