Dopamine and depression: a review of recent evidence. I. Empirical studies.

This paper reviews evidence from human, predominantly clinical, studies, relevant to the hypothesis that depression involves reduced levels of dopamine (DA) function. With the exception of Parkinson's disease, there is little evidence that treatments which decrease DA function are potent inducers of depression, but it is argued that such a relationship might not necessarily be expected. There is good evidence that the nigro-striatal DA system is underactive in retarded depressions, and some evidence that DA agonists are therapeutically effective in these cases. It remains unclear whether changes in DA function are primary or secondary.