The Association of Depressive Symptoms With Plasma C-Reactive Protein in Patients With Major Depressive Disorder Under Treatment

This study evaluates the relationship between plasma high sensitive c-reactive protein (HSCRP) in patients with Major Depressive Disorder (MDD) under therapy.

This cross-sectional study included 90 patients with MDD that had been diagnosed previously to confirm their matching «DSM-5 criteria for MDD version 7.0.2,» employing the «mini-international neuropsychiatric interview.» Also, they were on antidepressants prescriptions for at least 4 months. The criteria of MDD were based on the self-administered inquiry forms for evaluating depression severity, comprising the 9-item Patient Health Questionnaire (PHQ-9) depression module. A venous blood sample was collected from all participants for White Blood Cells (WBCs) counts and HSCRP assays. Besides their BMI calculations, SPSS v. 23, was used for all statistical tests.

HSCRP mean serum levels were within normal ranges among MDD patients. The Mean±SD age of the MDD patients was 39.5±0.9 years, and most of them were obese; their Mean±SD BMI was 32.9±15.8 kg/m2. The mean WBCs count of the participants was within the normal ranges. The ratio of male/female participants in this study was 1.64:1. There was a non-significant difference between the sexes in all study parameters: no significant variations in the distribution of HSCRP levels according to the scores of depression severity. There was no significant variation in the distribution of WBCs counts according to the severity of depressive thoughts. A receiver operating characteristic curve (when tested for the diagnostic ability of HSCRP) revealed poor predictability to distinguish those with severe MDD from those with no or mild depressive thoughts: area under the curve=0.484, sensitivity=0.52, specificity=0.46, and P>0.05. 

The outcomes of our study highlighted the importance of low-grade inflammation as a risk factor of the onset or even worsening of depression in patients with MDD. This finding is reflected by a significant difference in the mean levels of serum HSCRP between those having mild and severe PHQ-9 scores. However, the mean serum levels of HSCRP were not correlated with the severity of depressive symptoms.