Epidemiology of functional neurological disorder, active component, u.S. armed forces, 2000–2018

Functional neurological disorder (FND) is a complex neuropsychiatric disorder characterized by abnormal or atypical sensorimotor, gait, dissociative, or special sensory symptoms in the absence of structural nervous system lesions to explain the symptoms. Several factors are thought to be associated with FND, including comorbid mental health conditions; exposure to physical, emotional, or sexual trauma; young age, and low socioeconomic status. U.S. military service members may be at increased risk for FND because of the prevalence of some of these factors. The current study evaluated the incidence of FND in the U.S. Armed Forces between 2000 and 2018. The overall incidence rate was 29.5 per 100,000 person-years (p-yrs), with the highest rates among women and individuals less than 20 years old. The overall median annual prevalence rate was 37.2 per 100,000 persons. In addition, there were 162 medical evacuations out of the Central Command (CENT-COM) area of responsibility for FND during the study period. Most medical evacuations occurred among men and those with no history of depression or post-traumatic stress disorder (PTSD).