High-sensitive C-reactive protein (hs-CRP) has been used to assess low-grade immune system activation. In a population-based cohort hs-CRP was associated with functional somatic symptoms (SS), particularly with general and musculoskeletal functional SS clusters.

Immune system dysregulation has also been reported in depression that is frequently associated to a high burden of SS.

We investigated the correlation between hs-PCR and SS in depressed patients.

123 outpatients (M/F = 58/65; mean age 48,6 ± 14,8) during a Major Depressive Episode were recruited at the Institute of Psychiatry of the Catholic University in Rome. Severity of depression was assessed with the HAM-D scale. The somatization factor of the HAM-D (somatic anxiety, gastrointestinal symptoms, general somatic symptoms, hypochondria, weight loss) measured SS burden. A blood sample was collected to determine hs-CRP.

Hs-CRP and depression severity were not correlated, while hs-CRP and SS were (r = -0,27; p = 0,001). Patients with higher (> 3) somatizazion factor had significantly lower hs-PCR values compared to patients with lower (≤3) somatization factor (2,47 mg/L ± 4.77 vs. 3.20 mg/L ± 4.44; p = 0,026).

In contrast with the hypothesized cytokine involvement in somatic features of sickness behavior, higher somatic burden correlates with lower immune activation.

The role of sickness behavior in experiencing SS and hs-CRP's use as valid indicator of cytokine production remain uncertain. Further studies are necessary, also to explore the relationship between HPA axis dysregulation and immune activation, possibly relevant to the interpretation of our results.