Pulvinar and Ventral Thalamic Nuclei Changes Occur Early Along the Psychosis Spectrum.

Psychosis may be conceptualized as a spectrum disorder, with psychotic experiences (PEs), fleeting, subtle symptoms not warranting clinical presentation-at its mildest end. The thalamus, particularly its pulvinar region, is implicated in coordinating cortical synchrony and attention, and may contribute to psychosis. Reduced pulvinar volumes have been observed in severe psychosis and in individuals lower on the spectrum. This study examines thalamic nuclei changes in young adolescents with PEs. A community-based sample of 95 adolescents aged 11-13 years (53 with PEs, 42 healthy controls) underwent magnetic resonance imaging (MRI), with thalamic nuclei volumes calculated using Freesurfer. Magnetic resonance imaging (MRI) was repeated at 2- and 5-year follow-up. Analyses of covariance and linear mixed-effects (LME) models assessed group-wise differences at each timepoint (TP) and longitudinally. Individual nuclei were recombined into anatomical composites (eg, pulvinar, ventral) for targeted analysis. Compared with controls, adolescents with PEs had significantly smaller left pulvinar composite volumes at TP2 (P = .01) and TP3 (P = .019). Linear mixed-effects revealed a significant longitudinal reduction in left pulvinar volume (P = .008, false discovery rate [FDR]-corrected) and a significant increase in left ventral volumes (P = .013, FDR-corrected). Thalamic changes linked to higher-risk psychotic states appear detectable in nonclinical adolescents with subthreshold PEs. This divergence from normative developmental trajectories may indicate early alterations in neural circuits governing attention, cortical synchrony, and dopaminergic function. Identifying such early deviations could refine our understanding of psychosis vulnerability. Replication in larger, more diverse cohorts is warranted to confirm these preliminary findings and assess their predictive value.