Could a mouth swab for cortisol levels change how we approach mental illness?

[youtube http://www.youtube.com/watch?v=jmRHVXm-3j0&w=600&h=315]

If you've never heard of cortisol, here's a quick primer:

Cortisol, known more formally as hydrocortisone (INN, USAN, BAN), is a steroid hormone, to be more specific a glucocorticoid, produced by the zona fasciculata of the adrenal cortex.^[1] It is released in response to stress and a low le…