According to a Harvard psychiatrist, about 25% of psychiatric patients don't have anything wrong emotionally, just physically, and treating their illness can cure their mental problems. So, you're not depressed after all, you just have lupus, Lyme disease, or maybe cancer. Yay!
According to Barbara Schildkrout's new book Unmasking Psychological Symptoms, some of the common things that therapists treat their clients for can be caused with medical intervention. The book aims to save patients hours wasted talking about their mothers on an squeaky leather couch and get them into a doctor's office instead.
Just like depression might be caused (or worsened) by the conditions above, if you're anxious you may have an overactive thyroid, if you're irritable you might have a brain injury, if you're hallucinating you might have epilepsy or, you know, a drug problem, and if you're psychotic, it's probably just from a venereal disease, not because of something awful that happened to you in your formative years. See, crazy, you really have nothing to worry about at all. Nothing a few pills won't fix!