Cerebellar gray matter reduction correlation with negative symptom severity in schizophrenia and bipolar subjects

The cerebellum plays a role in cognitive, linguistic, and emotional processing but its role in these disorders has not been fully studied. In this research we will be addressing to what extent regional cerebellar gray matter reduction is seen within individuals with schizophrenia or bipolar disorder, relative to individuals without psychosis, and how that reduction correlates with the severity of the negative symptoms.

To investigate this question, we will analyze T1-weighted, structural neuroimaging data collected from seven different testing sites as a part of the Bipolar and Schizophrenia Network on Intermediate Phenotypes (BSNIP) project, with a total of 665 subjects.  All data was collected with IRB oversight and approval and has been shared through the NIH repositories. The data collected includes cerebellar gray matter volumes, family relations, testing site, age, gender, diagnosis, Negative Symptoms Scale (PANSS) scores, global cerebellar volume, and total intracranial volume. We will conduct a linear regression of regional cerebellar gray matter volumes as a function of the diagnostic group, taking into account age, gender, total brain volume, family membership, and scanning site.  Within the cases, we will use a similar model to relate cerebellar volumes to negative symptoms experienced. 

The analysis revealed no significance between the size of left Crus I and diagnostic group or Negative symptom PANSS score. 

The comparison of gray matter measures across schizophrenia and bipolar disorder has historically shown that the deficits in schizophrenia are worse than in bipolar disorder. However, these results explicitly examine cerebellar contributions to the diagnosis and the symptom patterns. Further research could address the specific neuronal connections disrupted by this decrease in cerebellar gray matter volume leading to not only a more holistic understanding of schizophrenia negative symptoms but may also illuminate neuronal pathways involved in negative symptoms that have been neglected in the past.