The present invention relates to a diagnostic test for testing susceptibility of individuals to inflammatory diseases such as rheumatoid arthritis and to means to evaluate potential treatment of arthritis with therapeutic agents directed at the central nervous system (CNS), designed to by-pass the CNS defect. The invention also provides means for evaluating and predicting response to stress in individuals. A counter-regulatory feedback loop exists between the immune and central nervous systems, in which the immune or pro-inflammatory mediators stimulate corticotropin-releasing hormone (CRH) activation of the hypothalamic-pituitary-adrenal (HPA) axis hormonal cascade. The resultant increase in plasma glucocorticoids serves to restrain and limit the intensity of the inflammatory-immune response, through the potent immunosuppressive/anti-inflammatory actions of the glucocorticoids.