Biogen Idec (NASDAQ: BIIB) and Elan Corporation, plc (NYSE: ELN) have announced results from a one-year, longitudinal health outcomes study (n=324) in which patients with multiple sclerosis (MS) who received 12 infusions of TYSABRI (natalizumab) reported improvements in quality of life (QoL) measures, as well as reduced fatigue and overall improved cognitive function, as measur...