Functional neurological disorders in Parkinson disease

Area of Science:

• Neurology
• Psychiatry
• Movement Disorders

Background:

• Parkinson disease (PD) is a neurodegenerative disorder affecting motor function.
• Functional neurological disorders (FND) involve neurological symptoms inconsistent with established neurological disease.
• The association between PD and FND requires further investigation to understand demographic and clinical differences.

Purpose of the Study:

• To identify the demographic and clinical characteristics of Parkinson disease patients with co-occurring functional neurological features (PD-FND).
• To compare these features against PD patients without functional neurological disorders (PD-only).

Main Methods:

• Data from 53 PD-FND patients across eight centers were extracted using a standardized form.
• PD-FND patients were matched with PD-only patients for age, gender, and disease duration.
• Logistic regression analysis was employed to compare the groups, accounting for clustering effects.

Main Results:

• PD-FND patients were predominantly female (68%) and experienced a longer delay to PD diagnosis.
• Compared to PD-only, PD-FND showed higher rates of dyskinesia, depression, anxiety, and levodopa-equivalent daily dose.
• PD-FND patients had lower motor severity, greater healthcare resource utilization, and increased likelihood of pre-existing psychiatric disorders and family history of PD.

Conclusions:

• A distinct subtype of PD with functional neurological features exists, often familial and characterized by greater psychiatric disability and healthcare resource use.
• Functional manifestations may act as prodromal symptoms in approximately one-third of PD patients.
• This subtype highlights the complex interplay between motor, psychiatric, and functional aspects in Parkinson disease.