Inflammatory profile in depression and associated clinical and sociodemographic features in a Middle-Eastern North-African population.

BACKGROUND: Evidence of the presence of an inflammatory syndrome in depressive disorders has aroused great interest among researchers but results were heterogeneous and almost all previous studies involved patients from Europe or North America. The objectives of the current study were to determine the prevalence of biological inflammatory syndrome among patients with depression in a Middle-Eastern/North-African population and to examine the associated sociodemographic and clinical factors.

METHODS: We conducted a cross-sectional descriptive and comparative study including 65 patients and 30 healthy controls. The patients had an untreated major depressive episode and no inflammatory medical conditions; they were recruited in the psychiatry outpatient clinic in Razi hospital - Tunisia over an eight-month period ranging from May to December 2012. We examined sociodemographic and clinical characteristics and both groups had an inflammatory balance including: high sensitive C-reactive protein, interleukin 6, serum protein electrophoresis, haptoglobin and orosomucoid. A standardized inflammatory protein profile for age and sex was performed.

RESULTS: High sensitive C-reactive protein levels did not differ significantly between patients with depression and controls. The assay results of Interleukin 6 in our study showed higher values in patients with depression than in controls (p=0.024). Albumin was found to be increased in patients with depression (p<0.001). The dosage of the alpha-1-globulin including the orosomucoid and of the alpha-2-globulin including haptoglobin, showed that patients with depression had higher values than controls (p<0.001). The inflammatory protein profile (which consists of a synthesis of three inflammatory proteins: high sensitive C-reactive protein, haptoglobin and orosomucoϊd) showed a trend towards higher levels of inflammation among patients with depression than among controls.

LIMITATIONS: The relatively small number of subjects decreased the statistical power and the cross-sectional setting does not allow us to draw any conclusions about cause-to-effect relationships. Although we tried to exclude people with current infections, a small percentage of subjects may have had subclinical infections. The Body Mass Index, a parameter that might affect the levels of the investigated inflammatory markers, was not measured.

CONCLUSION: The existence of inflammation in depression has been proven by the results of four meta-analyses and over a hundred studies. However, the generalization of this finding is yet to be confirmed. It seems more likely that inflammation concerns a subgroup of patients with depression. Studies targeting this particular subgroup could provide new therapeutic approaches.