Despite pioneering findings on immune functions in various depressive syndromes, few recent studies focus on the role of inflammation and its potential in generating novel antidepressant therapies. We suggest that geriatric depression is the behavioral syndrome par excellence in which inflammatory processes are likely to play an etiological role. We base this assertion on the following observations: Geriatric depression occurs in the context of medical and neurological illnesses in which inflammatory processes are part of their pathogenesis. Both aging and depression are associated with pronounced and prolonged immune responses. Brain areas related to mood processing, have increased inflammatory responses during aging. Moreover, the connectivity among mood regulating structures may be modulated by inflammatory responses. Geriatric depression exacerbates the pathology of its comorbid medical and neurological disorders raising the question whether depression-related inflammatory changes mediate the worsening of their outcomes. Finally, geriatric depression often occurs in persons exposed to chronic stress, a state precipitating geriatric depression and triggering pro-inflammatory responses.
The clinical lesson derived from the available information is that depressed older adults should be examined for inflammatory disorders or risk factors of inflammation. It is premature to use anti-inflammatory agents in the treatment of geriatric depression. However, treatment of co-morbid conditions increasing CNS inflammatory responses can have general health benefits and should be part of clinical practice. Neuroimaging may identify microstructural abnormalities and dysfunction of neural networks associated with inflammatory processes accompanying geriatric depression. Transgenic animal models may help to identify candidate anti-inflammatory agents that later may be tested in clinical trials of geriatric depression.