Altered brain entropy and functional connectivity patterns in generalized anxiety disorder patients

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Generalized anxiety disorder (GAD) is a common condition characterized by excessive worry.
• Previous research on GAD using resting-state functional MRI (fMRI) primarily focused on static, linear brain features.
• The nonlinear dynamics of brain signals in GAD remain underexplored.

Purpose of the Study:

• To investigate nonlinear dynamic complexity in GAD using resting-state fMRI.
• To compare brain entropy and functional connectivity between GAD patients and healthy controls.
• To assess the diagnostic potential of these brain features.

Main Methods:

• Resting-state fMRI data from 38 GAD patients and 37 healthy controls were analyzed for approximate entropy (ApEn) and sample entropy (SampEn).
• Brain regions with significant entropy differences were used as seeds to examine whole-brain resting-state functional connectivity (RSFC).
• Correlation analyses explored the relationship between brain entropy, RSFC, and anxiety severity. A linear SVM was employed for classification.

Main Results:

• GAD patients exhibited increased ApEn in the right angular cortex (AG) and increased SampEn in the right middle occipital gyrus (MOG) and inferior occipital gyrus (IOG) compared to controls.
• GAD patients showed decreased RSFC between the right AG and the right inferior parietal gyrus (IPG).
• The SVM model achieved 85.33% accuracy in distinguishing GAD patients from controls, with ApEn in the right AG positively correlating with anxiety scores.

Conclusions:

• GAD is associated with increased nonlinear brain signal complexity (ApEn) in the right AG and decreased linear RSFC involving the right IPG.
• Combining linear and nonlinear brain signal features shows promise for diagnosing psychiatric disorders like GAD.
• This study highlights the potential of advanced fMRI analysis for understanding GAD pathophysiology.