IL6 and major depressive disorder: We aimed to investigate the effects of serum CRP and serum IL-6 on anxiety and depression symptoms and life satisfaction by using MR analyses in a study population less prone to collider bias, the population-based Trøndelag Health Study (HUNT) in Norway with 54% (HUNT3, 2006–08) to 69% (HUNT2, 1995–97) participation rates (Krokstad et al., 2013).