The Involvement of Thalamic Nuclei in Schizophrenia Patients with and without Auditory Verbal Hallucinations: A Brain Morphometry Study

Background: The thalamus, together with its associated nuclei and thalamocortical pathways, is crucial in understanding the neurobiological mechanisms underlying auditory verbal hallucinations (AVHs) in schizophrenia (SCZ). Purpose: The study investigates the role of thalamic nuclei in schizophrenia patients experiencing auditory verbal hallucinations (AVHs). Methods: A total of 21 healthy controls (HC), 22 schizophrenia patients without auditory verbal hallucinations (SCZ_AVH−), and 22 schizophrenia patients with auditory verbal hallucinations (SCZ_AVH+), aged between 19 and 65 years, were recruited. They underwent MRI scans, and participants in the SCZ_AVH+ group completed the assessment of the severity of different dimensions of auditory hallucinations and delusions using the psychotic symptom rating scale (PSYRATS). High-resolution T1-weighted imaging was utilized to analyze the volumes of the thalamic nuclei. Results: The volumetric analysis of the thalamic nuclei indicated a significant reduction (t = 2.64, P = 0.03) in the right medial geniculate nucleus (MGN) volume in the SCZ_AVH+ group (0.08 ± 0.01 cm3) compared to the SCZ_AVH− group (0.09 ± 0.01 cm3). Also, the SCZ_AVH− group (0.03 ± 0 cm3) showed a significant increase (t = −2.73, P = 0.02) in right habenular nucleus (HN) volume compared to the HC group (0.02 ± 0 cm3). Significant correlations were observed between the volume of the left MGN and psychotic ratings (r= −0.5), as well as between the volume of the right HN and psychotic ratings (r= 0.56). Conclusion: The volumetric changes are observed in both SCZ_AVH− and SCZ_AVH+ groups, mainly in the thalamic nuclei. Structural deficits in the MGN may distinguish schizophrenia patients with AVHs from those without.