Dyskinesia, Psychiatric Disorders Associated With Functional Neurological Symptoms in PD
Parkinson disease and functional neurologic disorders are discrete conditions that frequently coexist.
According to research published in the Journal of Neurology, Neurosurgery, and Psychiatry, a family history of Parkinson disease (PD), presence of dyskinesia, and pre-existing psychiatric disorders are associated with PD-related functional neurologic disorders (PD-FND). Additionally, patients with PD-FND exhibit greater healthcare resource utilization and higher levodopa-equivalent daily doses compared with PD-only controls.
Investigators obtained de-identified patient data from electronic health records of patients with PD-FND (n=53) who were attending 8 movement disorders centers in the United States, Canada, and Europe. Using a consecutive cohort of similar patients who recently attended the clinics, the investigators extracted 53 PD-only controls who were matched for age, disease, and gender.
As assessed by the Beck Anxiety Inventory and the Beck Depression Inventory, patients with PD-FND had higher anxiety (34±8 vs 17±7; P =.033) and depression (21±10 vs 14±8; P =.025) scores compared with PD-only patients. Patients with PD-FND were more likely to have a family history of PD (P =.036) and a pre-existing psychiatric disorder (P =.008). Additionally, PD-FND patients required significantly higher levodopa-equivalent daily doses compared with PD-only controls (972±701 mg vs 741±557 mg; P =.029).
Symptoms of FND occurred prior and simultaneous to the PD diagnosis in 26% and 8% of PD-FND patients, respectively. There was a significantly longer delay to PD diagnosis among patients who experienced FND symptoms prior to vs after the PD diagnosis (3.5±2.4 vs 2.1±2.4 years, respectively; P =.017). Approximately half of the cohort (55%) experienced rapid onset of functional symptoms, with gait/balance impairment as well as tremor being the most frequently recorded symptoms.
Additionally, higher rates of dyskinesia were observed among PD-FND patients vs controls (42% vs 18%, respectively; P =.023). Patients with PD-FND also used healthcare resources at a greater frequency than PD-only controls, including greater hospitalizations (1.2±1.9 vs 0.9±2.6 visits; P =.007) and healthcare-related phone calls to physician offices (34±45 vs 17±23 calls; P =.029).
Limitations of this analysis include the investigators' inability to obtain data on non-motor PD symptoms or on rates of healthcare utilization outside of the provider's healthcare system.
Recognizing FND in patients with PD “may warrant avoidance of iatrogenic harm and consideration of non-pharmacological strategies, such as cognitive behavioral therapy.”
Wissel BD, Dwivedi AK, Merola A, et al. Functional neurological disorders in Parkinson disease [published online March 16, 2018]. J Neurol Neurosurg Psychiatry. doi: 10.1136/jnnp-2017-317378