Relapsing-remitting Multiple sclerosis (MS) is a chronic and often disabling disease that has been linked to a wide range of symptoms. Traditionally, MS-related symptoms have been evaluated using functional assessments such as the Kurtzke Expanded Disability Status Scale (EDSS) and the Timed Up and Go (TUG) Test. Detecting subtle changes in kinetic function is a key component in the monitoring and measuring of disease progression as well as predicting outcomes in MS. The BeCare Link mobile application provides validated, quantitative measurements of physical and cognitive functioning to give high precision measurement of disease status and treatment outcomes. Natalizumab is an effective drug that modulates immunity and inflammatory burden over time. While clinical outcomes in controlled clinical trials have shown that Natalizumab results in a reduction in disease progression on the EDSS, there is an often-referenced anecdotal effect reported by patients treated with Tysabri that they feel closer to their overall pre-MS sense of well-being, such as improved speed of cognition, reduced fatigue, and swifter motor and sensory function. This was named "Feel Good Effect", or "Restoring Physiologic Homeostasis(RPH)". Quantification of this effect has not been addressed previously.

This is a prospective single-center study. The goal of this proposal is to use the BeCare App to (1) determine changes in RPH for individuals with relapsing-remitting MS (RRMS) before and after starting Natalizumab therapy and (2) Compare BeCare-derived with clinically-derived performance metrics. Changes in RPH will be determined by pre/post differences in EDSS scores and self-reported questions regarding mood, quality of life, function and participation. The hypothesis is that Natalizumab will be associated with a significant improvement in RPH that will be quantifiable through the use of the BeCare App. The aim is to enroll 20 subjects, recruited from Mount Sinai MS clinic or self referred by contacting the study contact information posted on ClinicalTrials.gov. Individuals included will be of ages between 18 and 60 years with diagnosed RRMS (relapsing-remitting MS) who were prescribed Tysabri (Natalizumab) by their physician. Potential participants will contact the coordinator via phone call or e-mail and will be consented. After consent, participants will download the BeCare mobile application and be instructed to perform tasks on the app at their home 3 times per week for 2 weeks. Once they schedule their first Tysabri infusion, participants will come to 4 in-person study visits. At each visit, they will perform multiple application-based and clinically-based assessments. The entire study protocol will last up to 32 weeks, including follow up. All procedures of this trial are non-invasive and imply minimal risk. All study procedures involve clinical assessments performed routinely as part of their clinical care. Risks involve loss of private information and falling during the study tasks. Drug administration is not part of the trial, and it will be given as part of clinical care.

Each assessment is performed by the clinician once and the application once. These assessments include the Expanded Disability Status Scale (EDSS), Timed Up and Go (TUG), Tap Task, Path Test, Transcription Test, Timed 25-foot walk, Coded Message Cognitive Test, Six-minute walk test, Contrast sensitivity test, Arm elevation test, Memory test, Vibration test, and the Stroop color and word test (SCWT), 9 Whole Peg Test, Red Saturation Test and self-reported mood, quality of life, function, and participation.