A recent study has identified both shared and disease-specific changes in the expression of immune-related genes in six major psychiatric and neurological disorders — schizophrenia, bipolar disorder, autism spectrum disorder, major depressive disorder, Alzheimer disease and Parkinson disease. The authors investigated 1,275 genes in 2,467 post-mortem brain samples from donors with one of these disorders or healthy individuals. Expression of more than 60% of the genes, predominantly relating to the innate immune system, was altered in at least one of the disorders. The results highlight dysregulation of the immune system as a common feature among these disorders and suggest a potential role for immune-related treatments.