Endogenous depression is highly correlated with low levels of serotonin in the central nervous system. Does this imply or suggest that this sort of depression just is this neurochemical deficit? Scorning such an inference, Antonio Damasio writes:If feeling happy or sad … corresponds in part to the cognitive modes under which your thoughts are operating, then the explanation also requires that the chemical acts on the circuits which generate and manipulate [such thoughts]. Which means that reducing depression to a statement (...) about the availability of serotonin or norepinephrine in general- a popular statement in the days and age of Prozac- is unacceptably rude.Damasio's thought is that depression is essentially a modification of how we perceive the world, reason about it, and make decisions about how to act in it - in other words, that it is essentially cognitive. A reduced level of serotonin might cause the said modification, but no adequate account of depression would identify the malady with its cause. A proper account would minimally need to say how cognitive processing is affected by a reduced level of serotonin. (shrink)