Childhood and contemporaneous inflammation in depersonalisation and derealisation: Longitudinal evidence from the Avon Longitudinal Study of Parents and Children.

Background: Depersonalisation (DP) and derealisation (DR) are dissociative experiences that disrupt an individual's perception of themself and their environment. Recent evidence suggests a potential role for inflammatory processes. This study examined longitudinal associations between interleukin-6 (IL-6), C-reactive protein (CRP), and DP and DR across development. Methods: Data were drawn from the Avon Longitudinal Study of Parents and Children. IL-6 was measured at age 9 (n = 2606) and CRP at ages 9, 15, and 24 (n = 3323). DP and DR symptoms were assessed at ages 12, 17, and 24. Generalised linear mixed models examined associations between inflammatory markers and DP and DR using both early-life and time-varying approaches. Results: IL-6 at age 9 was not associated with DP or DR at any age. Higher CRP at age 9 was associated with increased odds of DR at age 12 but reduced odds of DR at ages 17 and 24. Higher CRP at age 9 was also associated with reduced odds of DP at age 24. Time-varying analyses differed: higher CRP at 24 was associated with reduced odds of DR at 24, but CRP measured in mid-adolescence was not associated with DR at 17, highlighting differences between fixed childhood and time-varying inflammatory models. Conclusions: Inflammatory processes may relate differently to DP and DR across development. Childhood CRP showed associations with later DP and DR, whereas contemporaneous CRP was associated only with DR, suggesting differing developmental patterns. These findings may reflect immune adaptation or cognitive mechanisms involved in the maintenance of symptoms.