Neuropsychiatric phenotypes in functional movement disorder

Area of Science:

• Neuroscience
• Psychiatry
• Movement Disorders

Background:

• Functional movement disorder (FMD) is a subtype of functional neurological disorder, primarily defined by motor symptoms.
• Non-motor symptoms are frequently observed in FMD patients but are not well-characterized in relation to the motor phenotype.
• Understanding the interplay between motor and non-motor features is crucial for a comprehensive view of FMD.

Purpose of the Study:

• To explore novel neuropsychiatric FMD phenotypes by integrating movement disorder presentations with non-motor comorbidities.
• To identify patterns and clinical factors contributing to the development and maintenance of FMD.

Main Methods:

• A retrospective chart review of 158 FMD patients was conducted, involving deep phenotyping across neurological and psychiatric domains.
• Cluster analysis was used to identify patterns combining motor symptoms with somatic symptoms, psychiatric diagnoses, and psychological factors.
• Logistic regression models were employed to test the identified neuropsychiatric FMD phenotypes.

Main Results:

• Distinct FMD phenotypes emerged when stratified by episodic versus constant motor symptoms.
• Episodic FMD was associated with hyperkinetic movements, hyperarousal, anxiety, and trauma history.
• Constant FMD was linked to weakness, gait disorders, fixed dystonia, activity avoidance, and low self-agency; pain, fatigue, and health anxiety were common across phenotypes.

Conclusions:

• FMD is part of a broader neuropsychiatric syndrome, with patterns spanning the neurological-psychiatric interface.
• A transdisciplinary approach reveals identifiable clinical factors relevant to FMD development and maintenance.
• Recognizing these neuropsychiatric phenotypes can inform clinical management and treatment strategies.