Relationship between leptin and C-reactive protein in young Finnish adults.

CONTEXT: Leptin and C-reactive protein (CRP) concentrations are increased in inflammation, and both have been linked to increased risk for cardiovascular diseases. OBJECTIVE: The objective of the study was to explore in a population-based sample whether the relation between leptin and CRP is independent of obesity level and whether genetic causes of CRP elevation contribute to leptin levels. DESIGN: This was a population-based study including 1862 young adults (971 women; 891 men) aged 24-39 yr. SETTING: The study was conducted at five centers in Finland. MAIN OUTCOME MEASURES: Associations between leptin and CRP adjusted for obesity indices, risk factors, genetic variables, and lifestyle variables were measured. RESULTS: Women had 3.0-fold higher median concentrations of leptin (12.5 vs. 4.1 ng/ml) and 1.3-fold higher median concentrations of CRP (0.75 vs. 0.56 mg/liter) than men (P < 0.0001 in both comparisons). In univariate analyses, CRP and leptin were significantly intercorrelated (r = 0.47, P < 0.0001 for women; r = 0.46, P < 0.0001 for men). In multiple regression analysis including age, body mass index, waist circumference, insulin, lipids, systolic and diastolic blood pressures, smoking status, and use of oral contraceptives in women, leptin was the main determinant of CRP in men (P < 0.0001) and the second most important determinant in women (P < 0.0001). A Mendelian randomization test based on genetic variants in the CRP gene (five single nucleotide polymorphisms) provided no support for CRP as a causal agent for leptin. CONCLUSIONS: Leptin, obesity, and oral contraceptive use in women were the main factors related to CRP. The relation between leptin and CRP was independent of obesity and cardiovascular risk factors.

Depressive symptoms and C-reactive protein: the Cardiovascular Risk in Young Finns Study.

BACKGROUND: We tested the hypothesis that depressive symptoms in healthy young adults would be associated with elevated levels of C-reactive proteins (CRP). METHOD: We studied the association between depressive symptoms and CRP in 1201 young adults, as a part of the on-going population-based Cardiovascular Risk in Young Finns Study. Depressive symptoms were determined by responses to a revised version of Beck's Depression Inventory in 1992 and 2001. CRP and other known cardiac risk factors were measured in 2001. RESULTS: Higher depressive symptomatology in 1992 and in 2001 and their means score were related to higher CRP levels (B's range from 0.24 to 0.21, p < 0.001). These relationships persisted after separate adjustments for various risk factors including sex, age, education, oral contraceptive use, dietary fat, physical activity, alcohol consumption, smoking status, LDL-cholesterol, HDL-cholesterol, systolic blood pressure and history of acute infectious disease. Adjustments for obesity and triglycerides levels, however, somewhat attenuated the relationship between depressive symptoms and CRP. CONCLUSIONS: We concluded that higher levels of depressive symptoms are associated with higher levels of CRP, but this association may largely be attributable to obesity or triglycerides.