Elevated hs-CRP level is associated with depression in younger adults: Results from the Korean National Health and Nutrition Examination Survey (KNHANES 2016)

•Higher hs-CRP levels are independently associated with depressive symptoms in Korean population after adjusting for confounding factors.•The association between a high hs-CRP level and depression was more prominent in younger adults than in older adults.•Elevated hs-CRP level was significantly associated with an increased risk of depression only in younger adults. Reports on the association between the level of circulating high-sensitivity C-reactive protein (hs-CRP) and depression have been inconsistent. The aim of this study was to examine the association between hs-CRP and depression in a large sample. This study used data obtained from a representative Korean sample of 5447 people who participated in the first (2016) year of the seventh Korean National Health and Nutrition Examination Survey (KNHNES VII-1). Depression was identified using a cutoff of 5 on the Patient Health Questionnaire-9 (PHQ-9), and high hs-CPR level was defined as ≥ 3.0 mg/L. Participants with a high CRP levels had a significantly higher rate of depression than did those with a low hs-CRP levels (25.1% vs. 19.8%, p = 0.007). Serum hs-CRP was independently associated with the PHQ-9 total score after adjusting for potentially confounding factors (B = 0.014; 95% CI = 0.008–0.020). After controlling for body mass index (BMI), smoking, alcohol use problems, hypertension, diabetes, dyslipidemia, chronic illness related hs-CRP, and metabolic syndrome. Furthermore, elevated hs-CRP level was significantly associated with an increased risk of depression (adjusted OR = 1.44; 95% CI = 1.01–2.07) in younger adults, but no significant association was observed among older adults. These findings suggest a significant correlation between high hs-CRP levels and depression in younger adults. Further studies are necessary to investigate the age-specific association and the biological mechanism involved.