LEADING RESEARCHERS JOIN BIOGEN IDEC TO ADVANCE DRUG DISCOVERY FOR NEURODEGENERATIVE DISEASES

–Christopher Henderson and Richard Ransohoff to Lead and Enhance the Company's Neurology Research and Discovery Effort–

CAMBRIDGE, Mass., October 23, 2014, Biogen Idec (NASDAQ: BIIB) today announced that two leading neuroscientists have joined the company to advance its research in neurodegenerative diseases. Christopher Henderson, Ph.D., joins as vice president, Neurology. Richard Ransohoff, M.D., joins as senior research fellow, Neuroimmunology. The addition of these top researchers bolsters Biogen Idec's discovery engine.

Biogen Idec has extensive discovery efforts focused on neurodegenerative and neuroimmune diseases, including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis (ALS) and multiple sclerosis (MS). Drs. Henderson and Ransohoff will work collaboratively within Biogen Idec's research and development organization to identify and accelerate the development of new product candidates. Both will report directly to Spyros Artavanis-Tsakonas, Ph.D., senior vice president, chief scientific officer, Biogen Idec.

"Transformative medicines result from transformative science," said Dr. Artavanis-Tsakonas. "We are bringing together some of the brightest minds in research to create new ways of looking at devastating neurological diseases where there are few, if any, effective therapies. Chris and Richard will help accelerate our efforts to bring innovative new medicines to patients who desperately need them."

About Dr. Henderson

Dr. Henderson joins Biogen Idec from Columbia University, where he was the Gurewitsch and Vidda Foundation professor of Rehabilitation and Regenerative Medicine with joint appointments in the departments of Pathology and Cell Biology, Neurology and Neuroscience. While at Columbia, he co-founded and directed the Center for Motor Neuron Biology and Disease, the Columbia Stem Cell Initiative, and the High-Throughput Screening and Chemistry Shared Facility. He also currently leads Target ALS, a privately-funded collaborative consortium focused on seeding ALS drug development programs through the discovery and validation of novel therapeutic targets.

Spending much of his early career in France, Dr. Henderson was a co-founder of Trophos, S.A., a drug discovery biotechnology company focused on neurodegenerative diseases. In addition, he was director of the INSERM research unit on Neuronal Development and Pathology in Marseille and visiting scientist at Genentech. Dr. Henderson obtained his Ph.D. from the University of Cambridge (UK) in 1979.

About Dr. Ransohoff

Dr. Ransohoff  joins Biogen Idec from the Cleveland Clinic, where he served as director of the Neuroinflammation Research Center in the Department of Neurosciences of the Lerner Research Institute; professor of Molecular Medicine at the Lerner College of Medicine at Case Western Reserve University; and staff neurologist at the Mellen Center for Multiple Sclerosis Treatment and Research. Dr. Ransohoff's research has focused on the functions of chemokines and chemokine receptors in the development and pathology of the central nervous system.

Dr. Ransohoff is a leading neuroimmunologist who has served on numerous scientific advisory and editorial boards. He currently sits on the National Multiple Sclerosis Society's (NMSS) Medical Advisory Board. His extensive body of research encompasses more than 300 publications across the fields of neurology and neuroimmunology. As a physician scientist, he has been continuously named to the "best doctors in America" for his expertise in the clinical care of patients with MS. He also received the 2012 John Dystel Award from the NMSS and American Academy of Neurology for multiple sclerosis research. Dr. Ransohoff received his M.D. from Case Western Reserve University School of Medicine, where he was later a postdoctoral fellow in the Department of Molecular Biology and Microbiology.

About Biogen Idec

Through cutting-edge science and medicine, Biogen Idec discovers, develops and delivers to patients worldwide innovative therapies for the treatment of neurodegenerative diseases, hematologic conditions and autoimmune disorders. Founded in 1978, Biogen Idec is the world's oldest independent biotechnology company and patients worldwide benefit from its leading multiple sclerosis and innovative hemophilia therapies. For product labeling, press releases and additional information about the Company, please visit http://www.biogenidec.com.

Safe Harbor

This press release contains forward-looking statements, including statements relating to advances from our drug research and development efforts. These statements may be identified by words such as "believe," "expect," "may," "plan," "potential," "will" and similar expressions, and are based on current beliefs and expectations. These statements involve risks and uncertainties that could cause actual results to differ materially from those reflected in such statements, including risks and uncertainties associated with drug development and commercialization, as well as other risks and uncertainties that are described in the Risk Factors section of our most recent annual or quarterly report filed with the U.S. Securities and Exchange Commission. Any forward-looking statements speak only as of the date of this press release and we assume no obligation to update any forward-looking statements, whether as a result of new information, future events or otherwise.