Inflammatory processes associated with persistent (
chronic) infection have long been discussed as etiological factors in
psychiatric disorders. Studies have found that people with major depression have higher levels of pro-inflammatory
cytokines, for example,
IL-1,
IL-6, and
tumor necrosis factor-alpha, and
C-reactive protein. In
schizophrenia, many reports have described raised levels of
cytokines, for example, IL-6; and meta-analyses have confirmed these findings. Microglia cells are important in inflammatory processes, and positron emission tomography studies have shown microglia activation in both depression and
schizophrenia.As a consequence of the above findings,
immunomodulation is widely discussed as a potential treatment approach in both major depression and
schizophrenia. The
COX-2 inhibitor celecoxib was found to have a significant positive effect on major depression, not only in single studies but also in meta-analyses.
Celecoxib has also been studied in
schizophrenia and has shown efficacy, in particular, in early disease stages. The mixed COX inhibitor
aspirin (
acetylsalicylic acid) seems to have both protective and
therapeutic effects on
schizophrenia.This paper discusses the hypothesized role of
inflammation in major depression and
schizophrenia, including markers of
inflammation; pertinent studies on
celecoxib and
aspirin; and additional immunomodulatory therapeutic strategies.