The neurobiology of aging and the neurobiology of depression: is there a relationship?

The relationship between the biology of aging and the biology of affective disorders remains obscure, largely for two reasons. First, and most important, is the equivocal nature of the data that indicates that increasing age predisposes an individual to episodes of major depression. Second, is the lack of tools to assess neurotransmitter turnover and availability in humans. Indirect measures such as neuroendocrine function tests, platelet, plasma and CSF studies contain too many confounding factors, to allow for adequate testing of neurochemical hypotheses. Development of novel approaches based on dynamic brain imaging methods may ameliorate these shortcomings.