Does Fampridine SR Improve Cognitive Fatigue in Multiple Sclerosis Patients?

Treatment tested

• Dalfampridine

  Voltage-gated potassium channel blocker

Placebo or sham

• Placebo

Inclusion Criteria: * Males/Females who are ≥ 18 years old and \< 65 years old * Capable of understanding and complying with the protocol, including speaking and writing fluent English and having at least a 9th grade education * Have a diagnosis of Relapsing Remitting, Secondary Progressive or Primary Progressive MS, as per revised McDonald's Criteria * Have not received steroids in last thirty (30) days or a relapse in the last sixty (60) days, and whose MS is considered stable * Have a PASAT CF z-score that is worse than 1.5 SD below the mean (\<-1.5 SD). * Have an Expanded Disability Status Scale (EDSS) of ≤ 7.0 * Have given written informed consent prior to any study-related procedure not part of normal medical care, with the understanding that consent may be withdrawn by the subject at any time without prejudice to his/her future medical care * Are capable of performing the requirements of a NP test battery including at least 20/70 near visual acuity by near vision chart, with correction allowed * If female, must neither be pregnant nor breast-feeding Exclusion Criteria: * Have cognitive deficits caused by concomitant medication usage or other significant neurological/psychological disease e.g. Alzheimer's disease, Parkinson's disease, stroke, transient ischemic attack, Vascular Dementia, Huntington's disease, traumatic brain injury or chronic CNS infection * Have evidence of other medical cause(s) of cognitive impairment * Have evidence of major depression as determined by a positive BDIFS and clinician interview * Have a history of uncontrolled hypertension, tachycardia or cardiovascular or disease * Have a history or current presentation of seizure * Are currently taking compounded 4-aminopyridine or another form of fampridine * Have a known hypersensitivity to any medical or non-medical ingredient of the medication tablet. * Have evidence of renal impairment (creatinine clearance ≤ 80 mL/min) * Are taking medications that are inhibitors of the renal organic cation transporter 2 (OCT2) * Have a diagnosis of colour blindness

Multiple Sclerosis (MS) patients often complain of cognitive fatigue. There is currently no treatment for this symptom. Fampridine SR is a recently approved medication that improves walking ability and walking speed in MS patients. It is thought that it might have the same positive effect on cognitive fatigue. This study will compare fampridine 10mg twice a day to placebo in order to determine if there is any benefit of this medication for cognitive fatigue in MS.