Abstract
Tourette syndrome (TS) is a neurobehavioral disorder for which the neurological mechanism has not been elucidated. Voxel-based morphometry (VBM) studies have revealed abnormalities in gray matter volume (GMV) in patients with TS; however, consistent results have not been obtained. The current study attempted to provide a voxel wise meta-analysis of gray matter changes using seed-based d mapping (SDM). We identified ten relevant studies that investigated gray matter alterations in TS patients and performed a meta-analysis using the SDM method to quantitatively estimate regional gray matter abnormalities. Next, we examined the relationships between GMV abnormalities and demographic and clinical characteristics. Our results demonstrated that TS patients had smaller GMV in the bilateral inferior frontal gyri and greater GMV in the cerebellum, right striatum (putamen), and bilateral thalami (pulvinar nucleus) than healthy controls. A meta-regression analysis did not identify correlations between GMV changes and demographic or clinical variables. This meta-analysis confirmed significant and consistent GMV changes in several brain regions of TS patients, primarily in the cortico-striato-thalamo-cortical network.
Highlights
1234567890():,; 1234567890():,; 1234567890():,; 1234567890():,; Introduction Tourette syndrome (TS) is a neurological disorder characterized by primary motor and vocal tics, and it is frequently concomitant with obsessive–compulsive disorder (OCD), attention-deficit–hyperactivity disorder (ADHD), or other social and behavioral disturbances[1,2,3]
The inclusion criteria of the studies were as follows: (i) original research published in peer-reviewed English journals; (ii) studies using voxel-based morphometry (VBM) to analyze the changes in gray matter volume (GMV) of the whole brain; (iii) studies comparing the GMV between TS patients and healthy controls (HCs); and (iv) studies reporting whole-brain results in a stereotactic space (MNI or Talairach)
We found that the GMV of TS patients decreased in bilateral IFG, which was thought to be responsible for the inability of TS patients to control their behavior[15]
Summary
Selection of studies A systematic search was performed for relevant studies published in the PubMed, Web of Science, Embase, and Science Direct databases before July 31, 2020, according to the “Preferred reporting items for systematic reviews and meta-analyses” (PRISMA) guidelines[30]. Using SDM software (https://www.sdmproject.com/), we used the peak coordinates to recreate a map of the effect size. In SDM v4.31, a standard Montreal Neurological Institute (MNI) map of the GMV differences was recreated for each included study using an anisotropic Gaussian kernel that assigns higher effect sizes to the voxels that are more closely correlated with peaks. These anisotropic kernels are introduced to optimize the recreation of effect size maps and provide greater robustness because they do not depend on a full width at half maximum[37]. We performed a visual inspection of the heterogeneity analysis according to the AES-SDM tutorial It revealed that no significant inter-study heterogeneity occurred in the regions reported in the results (p > 0.005).
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