Background: The effects of depression on the immune system are well known. Recently, depression as a consequence of an immune disorder has received increased research attention. Here, we test the hypothesis that the depression-immunity association is a buffer zone between external stimuli, defence mechanisms, and intrinsic determinants.
Subjects and methods: Five hundred and forty-nine patients presenting with a major depressive episode completed the Beck Depression Inventory (BDI), Lazarus and Folkman's coping inventory, and the Family Adaptability and Cohesion Scale (FACES III). Lymphocyte subtypes were quantified using flow cytometry.
Results: Links between immunity and depression were confirmed: levels of CD3, CD4 and CD8 cells accounted for 12.7% of the variance in the BDI (p<0.001, linear regression; LR). The depression-immunity pairing interacted with family dynamics, coping mechanisms, and gender. Dynamics in the family of origin explained 11.4% of the BDI score (LR) and 1% of CD3 and CD4 levels (p<0.001, Pearson's r). Coping mechanisms were associated with 12% of the BDI score (p<0.001, LR), and the capacity of distancing oneself from one's problems was associated with 10.3% of CD3, CD8, and CD16/56 levels (p<0.01, LR). BDI scores in women were 2.9 points higher than in men (p<0.01, t=2.379) and associated with a greater risk of immune depression (p<0.001, odds ratio=0.5).
Conclusions: External determinants (family), coping mechanisms, and internal determinants (such as gender) simultaneously influence a depression-immunity pairing. Sometimes these factors act more on the mood component, sometimes more on the immune component. The two components also interact closely with each other.