Previous theoretical models predict that elevated inflammation may predict later depressive symptoms, but bidirectional associations are possible. We examined whether depressive symptoms or inflammation predicts change in the other for a 3-month period in a sample of adults with acute coronary syndromes (ACS).
During hospitalization for their index ACS event (baseline) and then again 1 and 3 months later, 163 post-ACS patients completed the Beck Depression Inventory, a measure of depressive symptom severity with cognitive-affective and somatic-affective subscales. C-reactive protein (CRP) was also assessed at each visit; known correlates of depression and CRP were assessed at baseline. Path analyses were conducted to evaluate prospective associations between depressive symptoms and log-transformed CRP values and whether strength and/or directionality varied by specific depressive symptom dimensions.
Baseline total depressive symptom severity predicted a smaller decrease in CRP from baseline to 1 month (unstandardized parameter estimates [B] = 0.04, p < .001) controlling for all covariates, as did baseline cognitive-affective depressive symptom severity (B = 0.10, p = .02). Baseline somatic-affective depressive symptom severity did not predict change in CRP (B = −0.002, p = .94). CRP did not predict 1- or 3-month change in total, cognitive-affective, or somatic-affective depressive symptom severity. The results did not differ for men and women.
Greater cognitive-affective and total depressive symptom severity at the time of a cardiac event predicts a smaller decrease in CRP 1 month later, but there was no evidence in this study that CRP predicts change in depressive symptoms.
IL-6 = interleukin 6;
CRP = C-reactive protein;
ACS = acute coronary syndrome;
BDI = Beck Depression Inventory;
CFI = comparative fit index;
RMSEA = root mean square error of approximation;
BMI = body mass index