Selvaraj S, et al. - This study evaluated the relationship between the volume changes of cortical regions and microglial activation in cortical gray matter (GM), through brain TSPO imaging and gray matter volume in schizophrenia patients and in people at ultra high risk of psychosis. According to the findings obtained, microglial activity was related to the altered cortical volume seen in schizophrenia. However, longitudinal investigations were needed to determine whether microglial activation leads to cortical gray matter loss.

Methods

• For this study, 14 patients with schizophrenia and 14 ultra high risk for psychosis (UHR) subjects alongside 2 groups of age and genotype matched healthy controls received [¹¹C]PBR28 PET scans to index TSPO expression, a marker of microglial activation and a 3 T MRI scan.
• The relationship between the volume changes of cortical regions and microglial activation in cortical GM (as indexed by [¹¹C]PBR28 distribution volume ratio (DVR) were investigated.

Results

• The present study showed that the total cortical GM volume was significantly lower in SCZ than the controls [mean (SD)/cm³: SCZ = 448.83 (39.2) and controls = 499.6 (59.2) (p = 0.02) but not in UHR (mean (SD) = 503.06 (57.9) and controls = 524.46 (45.3) p = 0.3).
• Findings revealed that regression model fitted the total cortical GM DVR values with the cortical regional volumes in SCZ (r = 0.81; p < 0.001) and in UHR (r = 0.63; p = 0.02).
• A significant negative correlation was found between the TSPO signal and total cortical GM volume in SCZ with the highest absolute correlation coefficient in the right superior-parietal cortex (r = -0.72; p = 0.006).