Impaired Action Control in Patients With Functional Movement Disorders

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Functional movement disorders (FMDs) are a significant cause of neurological disability.
• The neural underpinnings of FMDs, particularly concerning action control, are not well understood.
• Existing research suggests links between FMDs and dysfunction in motor and prefrontal regions, potentially causing motor and cognitive deficits.

Purpose of the Study:

• To investigate specific components of action control in individuals with FMD.
• To utilize choice-reaction, stop-signal, and Simon tasks to assess action initiation, cancellation, and interference control.
• To compare action control abilities between FMD patients and healthy controls.

Main Methods:

• Prospective recruitment of 30 FMD patients and comparison with 53 healthy controls.
• Assessment of FMD motor symptom severity using the Simplified Functional Movement Disorder Rating Scale (S-FMDRS).
• Administration of choice-reaction, stop-signal, and Simon tasks to evaluate action control.

Main Results:

• FMD patients demonstrated reduced proficiency in suppressing incorrect responses (Simon task).
• Individuals with FMD were slower in canceling actions (stop-signal task) compared to controls.
• No significant correlations were found between neuropsychological measures, S-FMDRS scores, and action control performance.

Conclusions:

• Impairments in selective impulse inhibition and global action cancellation are characteristic of FMD.
• These deficits in inhibitory control are independent of general reaction time slowing.
• Enhanced understanding of action control mechanisms in FMD may facilitate the development of novel diagnostic and therapeutic approaches.