The Association Between Peripheral Complete Blood Count Parameters and Depressive Symptoms: A Cross-Sectional Study...

Background: Depression is a leading global cause of disability, increasingly recognized as a systemic condition involving low-grade immune-inflammatory activation and neuroendocrine dysregulation. Although complete blood count (CBC) parameters provide an accessible window into systemic physiology, empirical data from African countries, including Sudan, remain scarce. This study evaluated the associations between peripheral CBC parameters and depressive symptoms among adults in Eastern Sudan. Methods: A multistage community-based survey was conducted in Gadarif in Eastern Sudan. The sociodemographic characteristics and clinical data were collected through a face-to-face interview. Depressive symptoms were assessed through the Patient Health Questionnaire-9. Adults with a PHQ-9 score ≥ 10 were considered to have depressive symptoms. CBC parameters were assessed via venous blood samples using automated hematology analyzers. Multivariable linear regression with continuous PHQ-9 scores was performed. Results: Three hundred and thirty-two adults were enrolled. Of the 332 subjects, 166 (50.0%) adults were males, and 102 (30.7%, 95% CI = 25.7-35.7%) had depressive symptoms. There was a significantly higher median platelet count (308.0 × 10⁹/L vs. 291.5 × 10⁹/L; p = 0.025) and plateletcrit count (0.3% vs. 0.2%; p = 0.028), and a significantly lower hematocrit count (37.7% vs. 38.6%; p = 0.043) in adults with depressive symptoms. In the adjusted multivariable linear regression models, erythrocyte oxygen-carrying parameters remained associated with PHQ-9 scores, including hematocrit (B = -0.355, 95% CI = -0.511--0.199, p < 0.001) and hemoglobin (B = -0.621, 95% CI = -1.191--0.051, p = 0.033). Conversely, thrombocyte activation markers were associated with PHQ-9 scores, including mean platelet volume (MPV; B = 1.131, 95% CI = 0.221-2.041, p = 0.015) and total platelet count (B = 0.012, 95% CI = 0.00001-0.024, p = 0.047). Leukocyte profiles showed no association with PHQ-9 scores. Conclusions: Peripheral complete blood count parameters, specifically lower hematocrit and hemoglobin, alongside elevated MPV and platelet count, were associated with depressive symptoms in Eastern Sudan. CBC panels may a be useful inflammatory marker tool to detect the correlations with PHQ-9 scores in resource-limited primary care settings.