Similarity in Early Life Stress Exposure Is Associated With Similarity in Neural Representations in Early Adulthood.

Early life stress (ELS) has profound implications for developmental trajectories, yet the neural mechanisms underlying its long-term effects remain incompletely understood. In the present study, we examined whether interindividual similarity in ELS exposure aligns with similarity in neural representations and behavioral task performance in early adulthood. Leveraging a 20-year longitudinal dataset of Finnish families, we evaluated 87 young adults who underwent functional magnetic resonance imaging (fMRI) during an emotional go/no-go task. Intersubject representational similarity analysis (IS-RSA) was used to assess the associations between pairwise similarities in prospectively or retrospectively measured ELS, neural representations in 360 cortical regions, and task performance. We incorporated multidimensional scaling and Procrustes analysis to visualize interindividual differences in neural representational spaces. Prospective ELS-but not Retrospective ELS-was significantly associated with neural representational similarity across 40 cortical regions, including the anterior insula, frontal operculum, and anterior cingulate cortex. These findings highlight the systematic and chronic effects of more moderate ELS on brain development and emphasize the value of prospective measurements and advanced similarity analyses in capturing the nuanced influences of ELS. By integrating spatial and shape analytical techniques, the present study provides new insights into the long-term neurobiological correlates of ELS and introduces novel methodological tools for neurodevelopmental research.