Differentiating primary pathophysiologic from secondary adaptational processes

The following manuscript is mainly conceptual in nature. It should be read with reservation. since the relevance of its suggestions have yet to be pro ven. Basically it proposes two rules for the differentiation between primar y illness related pathophysiological vs. secondary adaptational processes. These rules may guide hypotheses generation for further research that is ai med at understanding psychiatric disorders and their shared and unshared me chanisms. For example, in the case of anxiety disorders and depression, it may be of interest to learn if their shared properties are of primary patho physiological or secondary adaptational significance. We first present some historical observations on the development of the concept of secondary ada ptational processes.'' We assume such adaptational processes are generated by the organism in order to compensate for primary pathophysiological malfu nction or impairment. Next, we propose rules that may enable the dissection of secondary adaptational from primary pathophysiological processes. We al so discuss the possible implications of designing studies to son out these processes, suggesting that the understanding of adaptational processes, may explain the effects of ''placebo treatment." Finally we illustrate the app lication of these rules by two examples: a) amygdala activation, a biologic al alteration shared by anxiety disorders and major depression and b) eleva ted plasma soluble interleukin 2 receptor, an unshared property by anxiety disorders and major depression. Also, the first example relates to a biolog ical perturbation associated with a primary pathophysiological mechanism, w hile the second represents a biological alteration associated with secondar y adaptational processes. (C) 2001 Wiley-Liss, Inc.