Altered Posterior Midline Activity in Patients with Jerky and Tremulous Functional Movement Disorders

Area of Science:

• Neuroscience
• Neurology
• Psychiatry

Background:

• Functional movement disorders (FMD) are a heterogeneous group of neurological conditions.
• Jerky and tremulous functional movement disorders (JT-FMD) represent a specific subtype requiring further investigation into underlying neural mechanisms.
• Resting-state network alterations are increasingly implicated in various neurological and psychiatric disorders.

Purpose of the Study:

• To investigate alterations in resting-state brain networks in patients diagnosed with JT-FMD.
• To compare functional connectivity and network dynamics between JT-FMD patients and healthy controls (HC).
• To explore potential correlations between network abnormalities, symptom severity, depression, and anxiety in JT-FMD.

Main Methods:

• Resting-state functional magnetic resonance imaging (rs-fMRI) data acquired from 17 JT-FMD patients and 17 matched HC.
• Independent Component Analysis (ICA) applied to identify and analyze the default mode network (DMN), central executive network (CEN), and salience network.
• Analysis of frequency distribution of network signal fluctuations and intra/internetwork functional connectivity.

Main Results:

• Patients with JT-FMD exhibited significantly reduced power in low-frequency fluctuations (0.01-0.10 Hz) within posterior components of the DMN (precuneus/posterior cingulate) and the dorsal attention network (DAN) of the CEN compared to HC.
• No significant differences were observed in intra- and internetwork functional connectivity between JT-FMD patients and HC.
• Symptom severity did not correlate with network measures; depression showed a weak correlation with medial prefrontal cortex connectivity, while anxiety did not correlate with network connectivity.

Conclusions:

• The observed alterations in the posterior DMN and DAN suggest that attentional dysregulation may be a fundamental pathophysiological mechanism in JT-FMD.
• These findings contribute to a better understanding of the neural underpinnings of JT-FMD.
• The study highlights the utility of analyzing frequency spectra of resting-state networks in characterizing functional neurological disorders.