C-reactive protein: A differential biomarker for major depressive disorder and bipolar II disorder

Abstract

Objectives We aimed to examine whether the C-reactive protein (CRP) level could be used to differentiate between major depressive disorder (MDD) and bipolar II disorder (BD II). Methods Ninety-six healthy controls, 88 BD II and 72 MDD drug-naïve patients in their major depressive episodes were enrolled. The fasting plasma level of high-sensitivity CRP was assessed at baseline and after treatment. Results The BD II patients presented significantly higher 17-item Hamilton Depression Rating Scale (HDRS) scores and CRP levels at baseline when adjustment for age, gender, and body mass index (P <  0.001 and P <  0.001, respectively). After treatment the CRP levels remained significantly different (P <  0.001), although the HDRS score was not significantly different between the BD II and MDD patients. A receiver-operating characteristic analysis showed that a baseline CRP level of 621.6 ng/mL could discriminate between BD II and MDD, with an area under the curve of 0.816 and a sensitivity and specificity of 0.699 and 0.882, respectively. Furthermore, the baseline CRP level greater than 621.6 ng/ml had 28.2 higher odds of a diagnosis of BD II (P <  0.001, 95% confidence interval: 10.96–72.35). Conclusions The level of CRP plays a role of biomarker to differentiate between MDD and BD II depression in both their depressed and euthymic state.

Keywords:

• Biomarker
• bipolar disorder
• C-reactive protein
• inflammation
• major depressive disorder

Acknowledgments

This study was financially supported by the National Science Council of Taiwan (NSC 93-2314-B-006-107, NSC 97-2314-B-006-006-MY3, NSC 98-2627-B-006-016, NSC 99-2627-B-006-014, NSC 100-2314-B-006-041-MY3, NSC 100-2627-B-006-012, NSC 101-2314-B-006-064-MY3 and NSC 101-2314-B-006-065), Ministry of Science and Technology, Taiwan (MOST 103-2320-B-006 -013 and MOST 104-2320-B-006 -024), Department of Health, Taiwan (DOH96-TD-D-113-041), and National Cheng Kung University Hospital (NCKUH-10301003). This research also received funding (D102-35001 and D103-35A09) from the Headquarters of University Advancement at the National Cheng Kung University, which is sponsored by the Ministry of Education, Taiwan, ROC. The authors wish to thank Mr. Chien Ting Lin for their administrative support.

Statement of interest

The authors declare that they have no conflicts of interest in relation to this work. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.