Philosophy, Psychiatry, & Psychology

Philosophy, Psychiatry, & Psychology 9.3 (2002) 255-259

On the Evolution of Depression

Mike W. Martin

Keywords: Depression, morality, mental disorders, psychobiology, evolutionary psychiatry.

In "Depression as a Mind-Body Problem," Walter Glannon outlines a psychosocial-physiological explanation of depression as a psychological response to chronic stress—today, especially social stress—in which cortisol imbalances disrupt neurotransmitters. Accordingly, treatment for depression should combine psychopharmacology and psychotherapy—a valuable reminder in light of the current restrictions on funding for health care (Hobson and Leonard 2001). My comments focus, however, on Glannon's objections to evolutionary theorists who explain our capacity for depression as adaptive to the natural and social environment. His objections are implausible because he fails to distinguish depression as a mood and a disorder.

What Is Depression?

Explaining the psychology, sociology, physiology, and evolution of depression presupposes knowing what depression is and hence what is being explained. As a blunt but important distinction, let us contrast depression as a mood and as a mood disorder.

As a mood, depression is a state of low spirits, typically involving painful and low affect (of a kind needing further specification). Not all negative low moods are depressions. It is notoriously difficult to distinguish depression from grief, sadness, gloom, and a host of additional ways to feel down—especially because today many people use "I'm depressed" as a blanket expression for virtually any low mood. For the purposes of this paper, it is not necessary to attempt a full-blown analysis of depressed moods (and emotions). I would emphasize, however, that depressed moods involve values. They involve negative evaluations of ourselves, major events in our lives, life in its entirety, or the values that have been guiding us. Typically, to be depressed is to experience such things as feelings of worthlessness, dejection about failures, despair and hopelessness, and loss of caring and commitment. Thus, we might be sad or grieving but not depressed because we retain a solid grip on what is valuable and worthwhile. In any case, there should be no general presumption that depressed moods are all bad or undesirable. Instead, we should be prepared to appreciate the importance of depressed moods in connection with questions of value, identity, and even moral insight (Martin 2000). Depressed persons are not necessarily sick.

In contrast, depression as a mood disorder is, by definition, pathologic. Moreover, usually it is not a depressed mood, although it involves depressed moods. On the one hand, depression as a disorder is defined as pathologic, a notion that is itself understood in terms of values—the values of health and, indirectly, moral values that define what is culturally acceptable. Thus, even severe [End Page 255] grief can be nonpathologic, even though it involves depressed moods, when it is within the range of "culturally-sanctioned responses" (APA 2000, xxxi). On the other hand, only sometimes is depression a single pathologic mood, as in major depressive episodes that can strike with a terrifying and suicidal severity (APA 2000, 375). Usually, however, the pathology is not a single depressed mood, but instead a longer-term state involving recurring depressed moods and additional features, such as poor concentration, insomnia, poor appetite or overeating, and so on. For some purposes, such as research funding and billing insurance companies and government health providers, these pathologies can be equated with what is currently in the DSM. Yet, there are many additional states of suboptimal health, in which the DSM criteria are only partly met.

What does Glannon mean by depression? He does not define it, but he makes it perfectly clear that he intends depression as a disorder. Or rather, it is a set of mental disorders, including the "depressive disorders" of major depressive disorder, dysthymic disorder, depressive disorder not otherwise specified, and a variety of bipolar disorders and some anxiety disorders. Glannon sometimes indicates his primary topic is "severe depression," which of course is not a DSM category (nor always a mark of pathology). For the most part, however, he says his topic is "chronic depression," which might suggest dysthymia, "a chronically depressed mood for most of...