Psychiatric disorders amply illustrate that “diseases” are intellectual artifacts which don’t exist naturally; the natural phenomenon is the mentally ill individual and no two are exactly alike.  Behavior assessment is the chief diagnostic tool, but increasingly, molecular profiling is untangling the subtle differences between, say, unipolar depression and bipolar states.  Recently, Ridge Diagnostics (San Diego, CA) developed a blood biomarker test for depression.  On the basis of ten biomarkers-related to metabolism, hormones, immune response and nerve transmission-the test produces a score of one to nine, with nine indicating a higher probability of serious depression.   MORE