Thalamic hyperperfusion in early schizophrenia: Associations with cognitive deficits and negative symptoms.

Objective: Thalamic abnormalities have been associated with clinical and cognitive symptoms of schizophrenia, yet their role in the early stages of the disorder remain unclear. This study aimed to examine and compare thalamic perfusion differences between first-episode schizophrenia (FES) and early-course schizophrenia (ECS), along with their associations with cognitive performance and symptom severity.

Methods: This study included 100 unmedicated schizophrenia patients aged 19-30: 50 FES and 50 ECS (<5 years, ≥2 episodes). Symptom severity was assessed with PANSS, and cognitive function was evaluated using the 5-KOG battery. All participants underwent brain SPECT and thalamic perfusion was analyzed using MIMneuro® software with whole-brain normalization and Z-score extraction. Group comparisons were performed using Chi-square tests, and associations between thalamic perfusion, cognition, and symptom severity were assessed using Spearman's rank-order correlations.

Results: Compared to FES patients, those with ECS showed significantly higher thalamic perfusion (P = 0.032). In the FES group, global thalamic hyperperfusion was negatively correlated with verbal fluency (ρ = -0.374, P = 0.007), while in the ECS group, right thalamic perfusion was positively correlated with negative symptom severity (ρ = 0.373, P = 0.008).

Conclusion: Thalamic hyperperfusion, especially in the right hemisphere, may reflect early cognitive and clinical changes in schizophrenia. Associations with negative symptoms and verbal fluency highlight its potential as a functional biomarker. These findings support the value of early-stage imaging and warrant further longitudinal research.