ABSTRACT
The main focus of depression research for the past few decades has been the neurophysiological mechanisms of serotonin depletion including the neurotrophic effects of this depletion, the neuroendo-crinological mechanisms of stress, the neuro-immunological equivalents of these mechanisms, and their interactions with sleep mechanisms. The reason the research programmes have been followed cannot possibly be because the researchers concerned seriously thought that depressive feelings (let alone major depression) are actually caused by low levels of serotonin. This chapter suggests that the “something else” most likely has to do with the brain mechanisms that actually generate depressive feelings. The differential diagnostic criterion suggests that depression can be easily mistaken for bereavement, which, in turn, suggests that depression is characterised by a complex of feelings that closely resembles those associated with grief. Although the opioid-driven attachment systems might be the pivotal mechanism in depression, there are many associated mechanisms that mediate the various depressive subtypes.
