Alexithymia and tissue inflammation

Altered immune responses are seen in depression, and recent data suggest that similar changes could also be observable in alexithymia. We examined whether the inflammatory markers high-sensitivity C-reactive protein (hs-CRP) and interleukin (IL)-6 are independently related to alexithymia or its factors in a population-based sample.

This study formed a clinical part of the Kuopio Depression (KUDEP) general population study focusing on the mental health of a general population of adults aged 25-64 years (n = 308). Alexithymia was measured using the Toronto Alexithymia Scale (TAS-20), and depressive symptoms were assessed using the Beck Depression Inventory (BDI-21).

The levels of IL-6 (in picograms per milliliter) and hs-CRP (in milligrams per liter) were significantly higher in alexithymic than in nonalexithymic subjects (IL-6 effect size, ES: 0.50; hs-CRP ES: 0.27). The BDI scores, hs-CRP and IL-6 explained 33.5% of the variation in TAS scores in the whole study population. According to logistic regression analysis, hs-CRP but not IL-6 increased the likelihood of belonging to the alexithymic group. This observation remained unaltered after additional adjustments for chronic inflammation-related disorders, the use of inflammation-modulating medications and depressive symptoms.

Our findings suggest that the association between hs-CRP and alexithymia resembles that observed in depressed patients. It is, however, independent of depressive symptoms. These findings widen our view on the stress-alexithymia concept.