Brain scans reveal cortical thinning and rewired signaling in Parkinson’s disease

People with Parkinson’s disease show not only localized thinning of the brain’s outer cortex but also altered patterns of directed signaling between that cortex and more distant regions, according to a new imaging study combining structural and functional magnetic resonance imaging. The research, conducted by a team at Taihe Hospital in Shiyan, China, examined whether the cortical regions that physically degenerate in Parkinson’s disease are also the ones whose network connections change, using a method that attempts to infer the direction of information flow between brain areas.

The study involved 62 patients with Parkinson’s disease and 46 healthy controls, all of whom underwent both structural MRI and resting-state functional MRI. The researchers used FreeSurfer software to measure cortical thickness across the whole brain. Two regions emerged as significantly thinner in the patients: the right medial superior frontal gyrus, an area associated with frontal-executive functions, and the right precentral gyrus, a key motor region. No region showed significantly greater cortical thickness in the patients than in the controls. These two thinned areas then served as seed regions for a voxel-wise Granger causality analysis, a technique applied to resting-state fMRI data that estimates whether activity in one region predicts subsequent activity in another, providing a directional measure of functional connectivity.

The connectivity analysis revealed a mixed pattern of increases and decreases in directed interactions. Compared with the controls, the patients showed increased directed influence from the medial superior frontal region to the left inferior temporal gyrus, and from the precentral gyrus to the calcarine cortex and medial visual cortex. At the same time, decreased directed influence was observed from the precentral gyrus to the left supramarginal gyrus, as well as reduced input to the precentral gyrus from the right superior temporal gyrus and from a left olfactory-related region. The findings suggest that the structural loss of cortical tissue in frontal-executive and motor areas is accompanied by a reorganization of how those areas communicate with distributed sensory and associative networks across the brain.

The study also explored whether these imaging measures related to cognition. Patients completed the Montreal Cognitive Assessment, and the researchers tested associations between imaging measures and test scores using partial correlations adjusted for age, sex, and education level. Cortical thickness in the right medial superior frontal gyrus was positively associated with cognitive scores, and this association remained significant after Bonferroni correction for seven exploratory correlation analyses, with a partial Spearman’s correlation coefficient of 0.847 and a p value below 0.001. No other imaging measure reached the corrected significance threshold. The authors caution that medial superior frontal cortical thickness may be related to global cognitive performance, a possibility that would require further investigation to confirm. As a cross-sectional comparison of a single patient group and control group, the study identifies patterns of structural and network change associated with Parkinson’s disease at one point in time; it does not establish how these changes develop over the course of the illness or whether they drive symptom progression.

Subject of Research: Cortical thickness and directed functional connectivity changes in Parkinson's disease measured with MRI and Granger causality analysis

Article Title: Cortical thinning and altered directed connectivity in Parkinson’s disease: a cortical thickness–guided voxel-wise granger causality study

Article References: Cheng, D., Wang, Y., Liu, C., Cheng, X., Wang, M., Tuo, Y., Chen, W., & Wu, D. (2026). Cortical thinning and altered directed connectivity in Parkinson’s disease: a cortical thickness–guided voxel-wise granger causality study. Frontiers in Neurology, 17, Article 1967317. https://doi.org/10.3389/fneur.2026.1967317

Image Credits: AI Generated

DOI: 10.3389/fneur.2026.1967317

Keywords: Parkinson's disease, cortical thickness, Granger causality analysis, resting-state fMRI, effective connectivity, structural MRI, FreeSurfer, Montreal Cognitive Assessment, precentral gyrus, medial superior frontal gyrus, neuroimaging, cognition