Inflammation in psychiatric disorders

Abstract

One of the most promising research fields is the inflammatory component of major psychiatric diseases (depression, bipolar disorders and schizophrenia). Multiple recent reviews clearly demonstrate that depression, schizophrenia and bipolar disorder are associated with a dysregulation of immune responses as reflected by the observed abnormal profiles of circulating pro- and anti-inflammatory cytokines in affected patients. Considering the high rate of associated somatic comorbidity, major mental illnesses, especially bipolar disorders, have been proposed as multi-systemic inflammatory diseases affecting the brain as well as other organs. In parallel, chronic inflammatory diseases are known to have a high psychiatric comorbidity rate (especially with depression). The same overlap is also found in pharmacological drugs properties as several antidepressants (especially selective serotonin reuptake inhibitors), several antipsychotics and mood stabilizers have shown intrinsic anti-inflammatory properties [1,2]. We recently conducted a systematic review of the literature regarding the efficacy of anti-inflammatory drugs (classified according to their mechanisms of action) in MDD, schizophrenia and bipolar disorders) [3]. We found that polyunsaturated fatty acids (PUFAs) have anti-inflammatory properties and are effective in major depression with a good tolerance profile. One meta-analysis based on 5 trials indicated that COX-2 specific inhibitors showed effectiveness in schizophrenia. COX-1 inhibitors like low-dose aspirin may also have potential effectiveness in the three major disorders but further studies are warranted. Minocycline, an antibiotic that penetrates central nervous system, showed also effectiveness in schizophrenia. Anti-TNFalpha drugs showed important effectiveness in resistant depression with blood inflammatory abnormalities, but in only one randomized placebo-controlled trial [4]. However, in this trial, the anti-inflammatory drug was much more effective than classical antidepressants in patients with baseline elevated hs-CRP (a inflammatory marker).