The brain and immune system are involved in an intricate network of bidirectional communication. This relationship is vital for optimal physiological and psychological development and functioning but can also result in unwanted outcomes. In particular, this interaction plays an important role in cognition, mood and behaviour. Neuroinflammation is known to contribute to neurological and affective disorders including impaired learning and memory, depressive, anxiety and schizoaffective symptoms, as well as pain. The development of these conditions often occurs on the backdrop of pre-existing physical illnesses which give rise to increased activation of the immune system, such as cancer, obesity, infection and autoimmune disorders. Similarly, psychological states can alter regulation of the immune system. This has been most extensively studied in the context of stress and immune function. Understanding the underlying mechanisms that lead to the onset of inflammation-induced neuropathology and stress-induced immune suppression will contribute to the development of novel and effective treatment strategies for both the disease and its neurological side effects. In this research topic we explored the relationship between the immune system and the brain throughout life. We include both original research and review papers from animal, clinical and molecular perspectives.