Nevertheless, given the range of behaviours regulated by melanocortins and other, similar, messenger molecules, the suspicions that other psychiatric disorders in particular, obsessive-compulsive disorder are partly or wholly the product of a similar process seem entirely plausible.

ECONOMIST: Psychiatric disorders and immunity

The DSM committees already tried their damnedest to support their diagnoses with neuroscience or biomarkers, but no lab tests yet exist for depression, schizophrenia, bipolar or obsessive-compulsive disorder, or, for that matter, any other mental disorders.

WSJ: Book Review: DSM-5 | The Book of Woe | Saving Normal