TNF-α Increase in a Cohort of Depressive Patients

Background The model of neuroinflammation has been proposed as a possible explanation of depression. Investigations of serum levels of tumor necrosis factor- α (TNF- α ) in depressed patients have previously shown contradictory results of increased and decreased levels of TNF- α during the treatment of depression.Methods We compared the serum levels of TNF- α in two cohorts of patients suffering from depression (ICD-10 criteria): one cohort from a psychotherapeutic unit ( n = 18), where patients were treated with Cognitive Behavioral Analysis System of Psychotherapy (CBASP), and the other cohort from a psychiatric day care unit ( n = 16). Both cohorts were investigated at the beginning and at the end of treatment. The intensity of depression was measured by means of the Beck Depression Inventory, 2 nd edition (BDI-II) at both time points.Results We observed a statistically significant increase of TNF- α in the psychotherapeutic unit at time point 2 compared to time point 1 ( T = −14.71, p < 0.001), but not in the psychiatric day care unit. In both cohorts, BDI-II scores at time point 2 were significantly decreased compared to time point 1 (psychiatric day care unit: T = 3.32, p = 0.005; psychotherapeutic unit: T = 6.22, p < 0.001). There was a significant correlation in the psychotherapeutic unit at time point 2 ( r = −0.682, p = 0.02).Conclusion As TNF- α was increased at time point 2 in the psychotherapeutic unit but not in patients of the psychiatric day care unit, we propose the different durations of pretreatments in both cohorts and the associated processes of neuroinflammation as a possible explanation for our results. The lack of information about the time course of TNF- α in depression could in general explain the huge variety of TNF- α levels in different cohorts of depressed patients reported in the literature.