The Psycho-Immunological Model As a Psychosomatic Entity: a Literature Review of Interactions between Depression and Immunity.

BACKGROUND: A large amount of evidence has already shown associations between depression and immunity, a bi-directional relationship seems to be increasingly evident. We showed in several precedent studies that family dynamics (Dubois et al. 2016, Zdanowicz et al. 2015), some coping skills (Manceaux et al. 2016) or gender (Fagniart et al. 2016) are correlated with depression and/or immunity and change the way depression and immunity interact together.

METHOD: The objective of this review is to study the literature in search of older and recent evidence about how immunity and depression interact and which determinants influence this relationship. We searched on PubMed, PsycINFO, PsycARTICLES and Sciencedirect articles with the keywords immunity and depression and with coping, gender and family.

RESULTS AND DISCUSSIONS: Surprisingly we observed in the literature that depression is mostly correlated with both inflammatory and impaired immunity mainly for cell-mediated immunity. Recent studies showed that gender differences in immunity seems to explain in part some variabilities concerning depression and acute/chronic stress among men and women. There is evidence for a sexual dimorphism of the immune system. Coping style, perceived control or personality impact the immune system. There is evidence that childhood maltreatment or stress occurring early in life can exert persistent effects over a long period of time like a "biological scar".

CONCLUSIONS: There seems to be an individual and biological heterogeneity behind the label of major depressive disorder. We demonstrated the role of several modulators on immunity and depression such as gender, coping, personality, early-life stress or relationships. Many other modulators could exist and should be considered for further investigations.