Differences in biomarkers between unipolar and bipolar depression: A meta-analysis

Area of Science:

• Neuroscience
• Biochemistry
• Psychiatry

Background:

• Distinguishing between unipolar depression (UD) and bipolar depression (BDD) is clinically significant.
• Peripheral blood biomarkers offer a potential avenue for objective diagnostic measures.

Purpose of the Study:

• To conduct a meta-analysis comparing peripheral blood biomarker levels between UD and BDD patients.
• To identify potential biomarkers for the differential diagnosis of UD and BDD.

Main Methods:

• Systematic literature search of PubMed, Embase, Cochrane Library, and Web of Science databases up to August 2024.
• Meta-analysis using Stata 15.1 to calculate weighted mean differences (WMDs) and 95% confidence intervals (CIs).
• Inclusion of 31 studies comprising 24,923 patients.

Main Results:

• Bipolar depression (BDD) patients exhibited significantly higher levels of interleukin-6 (IL-6), white blood cells (WBC), neutrophil count (NC), uric acid (UA), and albumin compared to unipolar depression (UD) patients.
• Conversely, BDD patients showed significantly lower platelet counts (PC) and brain-derived neurotrophic factor (BDNF) levels than UD patients.
• Specific WMDs and CIs were reported for each biomarker, indicating statistically significant differences.

Conclusions:

• BDD is associated with distinct peripheral blood biomarker profiles compared to UD.
• Elevated IL-6, WBC, NC, UA, albumin, and decreased PC and BDNF levels in BDD patients may serve as potential diagnostic indicators.
• These findings highlight the utility of peripheral biomarkers in differentiating between UD and BDD.