Objective: Several studies have suggested the existence of thalamic volume reduction in patients with schizophrenia. However, the precise locus of volume reduction within the thalamus has scarcely been investigated. On the other hand, underdevelopment of the adhesio interthalamica [AI; Danos, P., Baumann, B., Kramer, A., Bernstein, H.G., Stauch, R., Krell, D., Falkai, P., Bogerts, B., 2003. Volumes of association thalamic nuclei in schizophrenia: a post-mortem study. Schizophrenia Res. 60 141-155], which bridges bilateral medial edges of the thalamus, has been reported in patients with schizophrenia. We assessed the volumes of mediodorsal nuclei (MDN) of thalami, level of AI development, and their interrelationship, in patients with schizophrenia.
Method: A sample of 58 patients with schizophrenia and 44 matched healthy volunteers underwent assessment with high-resolution 1-mm-thick anatomical MRI. Volume measurements of the MDN of the thalamus and whole thalamus were performed by manual tracing. The level of AI development was quantitatively defined as the maximal anterior-to-posterior length of the AI.
Results: Schizophrenia patients had significantly smaller volumes of bilateral MDN. AI ratings were twice as high in women than in men among the control subjects; however, no gender difference emerged in the schizophrenia group due to reduced ratings in female patients. No significant correlation was found between MDN volumes and AI ratings among both groups.
Conclusions: These results provide evidence of volume reduction of the MDN, and female-specific underdevelopment of the AI in schizophrenia. As we did not demonstrate a relationship between MDN volume and AI ratings, it is suggested that these two measures of medial thalamic abnormality are manifestations of different neuropathological processes in schizophrenia patients.