Fig. 2.

Partial least squares path modelling of hypothesized indicators to post-traumatic stress symptoms (PTSS). A: Hypothesized model in which treatment burden (Neurological Predictor Scale; NPS) is associated with PTSS both directly and indirectly via two mediators: (1) the experience of a distressing event and (2) fronto-limbic white matter (WM) microstructure. WM is indexed by radial diffusivity (RD) values from the left and right cingulum bundle (CG) and inferior fronto-occipital fasciculus (IFO). PTSS indicators include avoidance (Av), re-experiencing (Re), and arousal (Ar). Covariates include whether a typically developing control was a sibling of a patient (sibling status) and age at testing. B: Comparison model, excluding WM, testing whether treatment burden and distress alone are associated with PTSS as effectively as when WM is included. C: Anatomical control model testing whether the effect of WM on PTSS is specific to fronto-limbic tracts. WM is represented by RD values from control tracts, the left and right optic radiation (OR). The overall model structure and covariates remain the same. For all models, standardized path coefficients (β) are presented; significant paths are denoted by ‘∗‘, indicating p < .05. R² values indicate the variance explained for endogenous variables. Lambda (λ) values represent factor loadings for observed indicators.