Post-Poliomyelitis Syndrome (PPS) is the term describing the new problems affecting polio survivors many years after recovery from paralytic polio. Among the symptoms, fatigue is one of the most frequent and debilitating. In addition to physical incapacitation, the fatigue of PPS also affects mental function. The term “brain fatigue” is usually used by patients to express problems on the areas of attention, concentration, memory and clear thinking. Unfortunately, little is known about cognitive fatigue of PPS patients. This study is meant to examine if mental impairment is present in PPS patients and, if so, how it interferes on the self-function of patients. Patients will undergo an interview, clinical and neurological evaluation, and a battery of screening laboratory tests to make sure they are eligible for the study. Patients who qualify will undergo neuropsychometric tests in order to assay performance in the main areas of cognitive functioning. Through this organized approach we expect to be able to determine if mental fatigue is a significant problem affecting polio survivors, what areas are most affected, and how it may interfere with daily living.