Pro-inflammatory markers and fatigue in patients with depression: A case-control study, 2020, Pedraz-Petrozzi et al

[Dolphin]

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https://www.nature.com/articles/s41598-020-66532-6

• Article
• Open Access
• Published: 11 June 2020

Pro-inflammatory markers and fatigue in patients with depression: A case-control study

• Bruno Pedraz-Petrozzi,
• Elena Neumann &
• Gebhard Sammer

Scientific Reports volume 10, Article number: 9494 (2020) Cite this article

Abstract

The aim of this work was to investigate differences between depressed subjects (PG) and non-depressed healthy control participants (HCG) with regard to fatigue dimensions and inflammation.

For this purpose, 43 participants in the PG and 51 participants in the HCG were included in the study. IL-6, IL-1β, TNF-α, IFN-γ, and CRP were assessed in venous blood samples.

Fatigue and depression were assessed using the FIS-D and BDI-FS questionnaires.

Main results showed higher BDI-FS values in PG. Moreover, PG showed mean differences for fatigue dimensions when compared to the HCG.

For the pro-inflammatory markers, a moderate group effect was found between PG and HCG which was mainly caused by IL-6.

Correlations between TNF-α and BDI-FS, TNF-α and cognitive fatigue, TNF-α and psychosocial fatigue were found within the PG.

In the HCG, correlations were found between IL-6, TNF-α and somatic fatigue, as well as IL-6 and cognitive fatigue.

Significant correlations were found between the psychological variables in both groups.

All results were controlled for the confounding variables gender, age, BMI and multiple comparisons.

These results suggest the presence of inflammation in both depression and fatigue.

However, each correlates with different pro-inflammatory parameters, suggesting a biological heterogeneity.

 

[Woolie]

I had a look at this, thought it was fairly unexciting. Small sample size, straight-down-the-line division between "depressed" and "control" patients, and then throwing at lot of measures at the analysis so you can be sure something sticks. And then at the end, getting confused about whether you're actually studying depression or fatigue.

Seems to be moving us backwards not forwards. A few years ago, there were some pretty good studies showing that high levels of inflammatory markers like CRP, TNF-alpha and IL-6 were only reliably associated with certain symptoms of depression - specifically, the "somatic" ones that include things like low energy levels, fatigue, poor sleep, etc. Yep, the ones that aren't really the depression itself but we've got ourselves so messed up that we treat them as the same as what depression really is about (which is sad mood, loss of interest in life - generally, severe and otherwise inexplicable emotional distress).

This study is a good example:

Duivis HE, Vogelzangs N, Kupper N, de Jonge P, Penninx BWJH. Differential association of somatic and cognitive symptoms of depression and anxiety with inflammation: findings from the Netherlands Study of Depression and Anxiety (NESDA). Psychoneuroendocrinology. 2013;38:1573–85.
https://www.sciencedirect.com/science/article/pii/S0306453013000073