TNF-α Increase in a Cohort of Depressive Patients

Abstract

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, 2nd 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.