Immunity and psychiatric disorders: variabilities of immunity biomarkers are they specific?

Background: In previous studies we showed the interaction between depression and immunity. We observed that psychological stress seems to be important in this association. In this review we try to understand if psychological stress and immunity have similar or specific impact on the other psychiatric disorders. More generally we review literature to understand if specific immune alterations exist between the main psychiatric diagnoses.

Method: We studied the literature in search of variabilities between the different psychiatric disorders in terms of immunity especially inflammation. We search on Pubmed, PsycINFO, PsycARTICLES and Sciencedirect articles with the keywords immunity or inflammation and depression, anxious disorders and schizophrenia.

Results: Prevalence of inflammation in psychiatric disorders seems to be between 21 to 42%. Psychiatric disorders are correlated with elevated levels of CRP, pro-inflammatory cytokines (IL-6, IL-1β and TNFα) and anti-inflammatory factors (TGF β, IL-10, sIL-2, IL-1RA). IL-6 in childhood were associated with subsequent risk of depression or psychotic disorders in early adulthood and in a dose dependent manner.

Discussions: We found similar immune processes through the different disorders. Variations in cytokines levels seem paralleling various stages of the illness and treatment. Inflammatory markers are linked with severity and resistance to treatment and with subsequent risk of disorders.

Conclusions: Some inflammatory parameters could be considered as risk factor, severity, resistance, trait or state markers of a psychiatric disorder. Other studies are necessary to a better understanding of clinical implications of this heterogeneity.