[Neuro-immune interactions in psychopathology with the example of interferon-alpha-induced depression]

The use of interferon (IFN)-alpha for the treatment of viral diseases or cancers is associated with neuropsychiatric side effects in a large number of patients. The mechanisms by which cytokines induce these symptoms, as well as the vulnerability factors for these effects, have not been yet fully elucidated. Systematic clinical studies, combining biochemical approaches, functional brain imaging and treatment intervention, have been initiated to better understand the phenomenology, pathophysiology, and preventive strategies of the neuropsychiatric effects of IFN-alpha in patients with malignant melanoma or chronic hepatitis C. The findings indicate differential phenomenology and treatment responsiveness of the neurovegetative and mood/cognitive symptoms induced by IFN-alpha, suggesting distinct underlying mechanisms. Impaired neuroendocine function, fronto-striatal dysfunction and decreased monoamine were found to contribute to the pathophysiology of core symptoms of IFN-alpha-induced depression, including symptoms of mood alterations, cognitive dysfunction, anhedonia and psychomotor retardation. In addition, some behavioral and biological markers of the vulnerability for IFN-alpha-induced depression were identified. These findings provide important information concerning the relationship between cytokines and depression.