In the past century, considerable efforts to understand the nature of psychiatric disorders have been undertaken. There have been successes, and a few diseases with prominent psychiatric manifestations that were once prevalent are now rare in many parts of the world (e.g., pellagra 4 and neurosyphilis 5). These few triumphs stand in contrast to decades of frustration and occasional notoriety when highly publicized and plausible findings failed to replicate. Indeed, most psychiatric disorders have been intractable to approaches that were fruitful in other areas of medicine. Thus, psychiatric syndromes are generally referred to as “disorders” (illnesses that disrupt normal function) and only a few as “diseases” (disorders with known pathophysiology or structural pathology). An obvious goal of psychiatric research is to convert idiopathic disorders into pathophysiologically-defined diseases.
