IL6 and major depressive disorder: Prior studies have shown that anhedonia but not the depressive symptom is related to inflammatory markers, mainly CRP and IL-6 in MDD (Bekhbat et al., 2020; Kudinova et al., 2020; Majd et al., 2020; Rengasamy et al., 2021), which was consistent with our results suggesting the role of inflammation in patients with MDD with anhedonia.