ABSTRACT
“There is no single theory to account for the many facets of the biological psychiatry of major depressive disorders,” conclude the authors of an article that links stress and immune activation to depression (Dantzer et al., 2009, p. 133). Accordingly, in this chapter, I will bring together the main elements that have been identified in the biological matrix, while recognising that the origins of depression lie in how the psychosocial interacts with the biological. The recurrent theme will be that causality is multiple, complex, and only partially understood.
