IL6 and depressive disorder: In contrast, Kappelman et al. (Kappelmann et al. 2021) and Wium Andersen et al. (Kim Wium-Andersen et al. 2014) found no effect of serum CRP on depression, whereas Perry et al. (Perry et al. 2021) found no effect of serum CRP, but evidence of an effect of higher serum IL-6 on depression.