In addition, as we reviewed elsewhere, increasing evidence indicates that the augmented levels of proinflammatory cytokines, such as interleukin (IL)-6, IL-1β, TNF-α, and macrophage migration inhibitory factors that are found in RA patients, may play a role in the induction of depression through multiple biological mechanisms [49,50,51,52]. This evidence concerns the gene TNF and rheumatoid arthritis.