Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN) have announced six-month results of an ongoing, one-year longitudinal, observational, patient-reported outcomes study showing multiple sclerosis (MS) patients taking TYSABRI® (natalizumab) experienced an improvement in both their physical function and psychological well-being. Findings from the study, which was performed in conjunction with HealthCore Inc.