A large database documents the role of inflammatory processes in the development of neuropsychiatric symptom dimensions that are common to multiple psychiatric conditions. Mechanisms mediating this effect are believed to involve disturbances in monoamine and glutamate metabolism and function, through the action of inflammatory factors on two distinct enzymatic pathways, including the indoleamine-2,3-dioxygenase (IDO) and GTP-cyclohydrolase I (GCH-I) pathways. Alterations in these pathways contribute to profound structural and functional brain abnormalities associated with specific symptom dimensions. Increasing knowledge on immune-to-brain interactions is expected to facilitate the development and implementation of novel and innovative therapeutic interventions against inflammation targeting, at distinct levels of integration, mechanisms, processes, and brain circuits underlying the expression of specific clinical profiles. These strategies are crucial for a precision medicine in Psychiatry, tailored to the clinical and biological phenotypes of patients.