Psychiatric Comorbidities in Functional Movement Disorders: A Retrospective Cohort Study

Functional movement disorders (FMD) are characterized by abnormal movements and motor symptoms incongruent with a known structural neurologic cause. While psychological stressors have long been considered an important risk factor for developing FMD, little is known about the impact of psychiatric comorbidities on disease manifestations or complexity.

To compare characteristics of FMD patients with co-occurring mood and trauma-related psychiatric conditions to FMD patients without psychiatric conditions.

We performed a retrospective cohort study of patients seen in the University of Colorado Health system between January 1, 2015 and December 31, 2019. Patients were included if they had a diagnosis of FMD, determined by ICD-10 coding and ≥1 phenomenology-related diagnostic code (tremor, gait disturbances, ataxia, spasms, and weakness), and at least one encounter with a neurology specialist. Fisher's exact and unpaired t-tests were used to compare demographics, healthcare utilization, and phenomenologies of patients with psychiatric conditions to those with none.

Our review identified 551 patients with a diagnosis of FMD who met inclusion criteria. Patients with psychiatric conditions (N = 417, 75.7%) had increased five-year healthcare utilization (mean emergency room encounters 9.9 vs. 3.5, P = 0.0001) and more prevalent non-epileptic seizures (18.2% vs. 7.5%, P = 0.001). Suicidal ideation (8.4%) and self-harm (4.1%) were only observed amongst patients with comorbid psychiatric conditions.

Patients with FMD and comorbid psychiatric conditions require more healthcare resources and have greater disease complexity than patients without psychiatric illness. This may have implications for treatment of patients without comorbid psychiatric conditions who may benefit from targeted physiotherapy alone.