Impact of comorbid post traumatic stress disorder on multiple sclerosis in military veterans: A population-based cohort study

Background: Very little is known regarding the impact of post traumatic stress disorder (PTSD) on the course of multiple sclerosis (MS). Objectives: To explore the impact of pre-existing PTSD on MS relapses, magnetic resonance imaging (MRI) activity, and disability in a large population-based cohort. Methods: Military Veterans with MS and PTSD prior to symptom onset (MSPTSD, n = 96) were identified using the Department of Veterans Affairs MS databases. MSPTSD cases were matched to MS controls without PTSD (n = 95). Number of relapses, number of new T2 lesions and new gadolinium lesions on brain MRI, and neurological disability were abstracted between 2015 and 2019. Results: The mean annualized relapse rate was greater in the MSPTSD group versus controls (0.23 vs 0.06, respectively; p