STATISTICAL ANALYSIS OF CORTICAL MORPHOMETRICS USING POOLED DISTANCES BASED ON LABELED CORTICAL DISTANCE MAPS

Area of Science:

• Neuroimaging
• Computational Anatomy
• Psychiatry

Background:

• Neuropsychiatric disorders are associated with structural brain changes, particularly in cortical morphology.
• Labeled Cortical Distance Mapping (LCDM) quantifies these shape differences using distances from gray matter voxels to the cortical surface.
• Existing methods using LCDM summary statistics may not capture all available morphometric information.

Purpose of the Study:

• To investigate the robustness of pooled LCDM distance analysis to assumption violations.
• To explore the utility of pooled LCDM distances for detecting group differences in cortical morphometry.
• To identify specific morphometric alterations in the ventral medial prefrontal cortex (VMPFC) in major depressive disorder (MDD) and high-risk (HR) individuals.

Main Methods:

• Pooled LCDM distances from subjects within diagnostic groups (MDD, HR, healthy controls).
• Assessed the robustness of parametric and nonparametric statistical tests to non-normality and within-sample dependence of LCDM data.
• Applied the methodology to analyze gray matter morphometry in the VMPFC of MDD, HR, and healthy subjects.

Main Results:

• Classical parametric tests demonstrated robustness to non-normality and within-sample dependence in pooled LCDM data.
• Nonparametric tests were robust to within-sample dependence.
• Pooled LCDM distance analysis revealed significant morphometric differences in the VMPFC between groups.
• Specifically, decreased distances were observed in the VMPFC for individuals with MDD or at HR, suggesting cortical thinning.

Conclusions:

• Pooled LCDM distance analysis is a powerful and robust method for detecting group differences in cortical morphometry, even with assumption violations.
• The findings indicate significant alterations in VMPFC structure associated with MDD and high risk for the disorder.
• This methodology holds promise for application to other cortical structures and neuropsychiatric conditions.