An evaluation of the differences in thalamic nuclei and subnuclei among patients with schizophrenia and schizoaffective disorder.

AIM: This study aimed to examine volumetric differences in thalamic nuclei among patients with schizophrenia, schizoaffective disorder, and healthy controls to identify disorder-specific patterns of thalamic involvement METHODS: The study included 45 patients aged 18-65 years (25 with schizophrenia and 20 with schizoaffective disorder) without physical or neurological disease, and 26 healthy controls. Participants were assessed using the Positive and Negative Syndrome Scale, Clinical Global Impression scale, and Pittsburgh Sleep Quality Index; the Young Mania Rating Scale and Hamilton Depression Rating Scale were additionally applied in the schizoaffective group. Volumes of thalamic nuclei groups (anterior, medial, intralaminar, posterior, lateral, and ventral) and their subnuclei were measured using a probabilistic atlas-based segmentation method. Group differences were evaluated using multivariate analysis of covariance, controlling for age and intracranial volume.

RESULTS: Patients with schizoaffective disorder showed significantly reduced total right thalamic volume (p=0.001) and reduced volumes of the ventral posterolateral (p=0.006) and ventromedial nuclei (p=0.006) compared with schizophrenia patients and healthy controls. Reductions were also observed in medial and intralaminar nuclei associated with limbic function, attention,pain.

CONCLUSION: Schizoaffective disorder shows greater right-sided thalamic involvement than schizophrenia. These nucleus-level differences may help clarify the pathophysiology of schizoaffective disorder and support diagnostic relevance.