CRP and major depressive disorder: This biomarker, which has the advantage to be easily measurable in plasma, has been one of the most studied markers in relation to psychological variables, where some authors have found association between anxiety and depression levels (considered negative psychological variables) with higher levels of CRP [6,7,13], while other studies have found a negative correlation between CRP and positive affect and other positive psychological variables, including life satisfaction and psychological wellbeing, after adjusting for confounders [3,4,5].