Often obscured by symptoms and circumstances, depression is notoriously difficult to diagnose. In this program, case studies of patients with adult, childhood, and postnatal depression define the spectrum of the illness. The history of a patient with Cushing’s syndrome underscores the effects of cortisol on depression, while studies conducted by Oxford University and the University of Pittsburgh reveal the relationship of serotonin and glia to depression. Observations provided by patients, unsure of what is wrong with themselves and often feeling too ashamed or guilty to seek help, offer valuable insights. A BBC Production. (50 minutes)