Interleukin-6 and verbal memory in recurrent major depressive disorder

OBJECTIVE: To evaluate the possible association between peripheral levels of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) with immediate and delayed verbal recall in a group of recurrent depressed women. METHODS: Logical Memory Subtests of the Wechsler Memory Scale - Revised was administered to 30 patients with recurrent major depressive disorder with no clinical and psychiatric comorbidities. Blood samples were collected from 8:00 am to 9:00 am, before memory assessments. Plasma was stored and ELISA assay was used to detect IL-6 and TNF-alpha levels. RESULTS: There was a statistically significant association between IL-6 levels and immediate verbal recall (IVR) (B=-0.787, p=0.000) and delayed verbal recall (DVR) (B=-0.695, p=0.001) even after controlling for age, depression severity and body mass index. CONCLUSION: The results of this study indicated that low performances in IVR and DVR are associated with higher IL-6 levels in women with recurrent MDD. The results of this study suggest the existence of an association between inflammatory imbalance and cognitive impairment in MDD.