C-reactive protein is associated with pain-type somatic symptoms independent of mental health symptoms in adolescents: Evidence from the ALSPAC study.

Depression and anxiety disorders frequently first present during adolescence, and both conditions are often comorbid with the experience of pain-type somatic symptoms. Moreover, increased concentrations of blood-derived inflammatory markers, such as C-reactive protein (CRP), have been observed in both depression and anxiety. Altered neuroimmune activation may impact on pain signalling pathways in the nervous system, potentially playing a role in the relationship between mental health and pain-type somatic symptoms. This study conducted cross-sectional secondary data analyses of the Avon Longitudinal Study of Parents and Children (ALSPAC) dataset, using a sample of 2877 participants at age 18. Baron and Kenny's (1986) mediation framework was used to explore whether CRP acts as a mediator between depression and anxiety scores, and pain-type somatic symptoms. While CRP cannot be said to directly mediate the relationship in this sample, adjusted regression analysis found that CRP was a significant, independent predictor of pain-type somatic symptoms ( = .12, p < .001), independent of anxiety score ( = .20, p < .001), depression score ( = .38, p < .001), and the interaction term anxiety∗depression ( = -.15, p < .001), indicating that CRP may underly pain-type somatic symptoms, independent of mental health symptoms in adolescence. These findings highlight the potential role of inflammatory processes in adolescent pain, and suggest that future research should examine biological factors, including inflammatory markers not typically assessed in clinical settings, that could underly pain symptoms not fully explained by mental health.