Henry Barnett was born in Newcastle upon Tyne in England and moved with his parents to Canada as a child. He entered medicine at the University of Toronto where he graduated in 1944. He did his junior rotating internship at the Toronto General Hospital and later completed training in neurology in Toronto in 1950. After two years at Queen Square in London, UK, and later a research assistant in Oxford, he obtained a fellowship from the Royal College of Physicians and Surgeons of Canada (F.R.C.P.(C.)). From 1952 to 1967 he was neurologist at the Toronto General Hospital and from 1966 to 1969 Chief of the Division of Neurology at Sunnybrook Medical Centre. In 1969 he was invited to become the Chief of the Division of Neurology at The University of Western Ontario and Victoria Hospital in London, Ontario. From 1974 to 1984 he served as Chairman of the Department of Clinical Neurological Sciences at Western University. In 1986, he co-founded the Robarts Research Institute and was named its first Scientific Director.
Barnett is most famous for the North American Symptomatic Carotid Endarterectomy Trial (NASCET), which evaluated whether or not clearing a clogged neck artery in the hopes of averting stroke actually reduced a patient's risk of stroke or dying. "No one knew who needed surgery and who didn't," recalls Barnett. "So the director of the (U.S.) National Institute of Neurological Disease and Stroke at the time said: 'Barney, why don't you evaluate it?'" The rest, as they say, is medical history. NASCET showed that the invasive surgical procedure significantly reduced the risk of stroke in patients who had a carotid artery that was more than 70 per cent blocked - otherwise, the operation yielded only a moderate reduction in the risk of stroke in patients with moderate blockages (50 to 69 per cent) and did not at all benefit patients who had an artery that was less than SO per cent blocked. "That got us a reputation for knowing something about stroke," says the characteristically modest Barnett
Barnett’s extraordinary contributions to stroke research have changed the management of millions of stroke patients. The implementation of his research has prevented an unaccountable number of strokes and continues to save lives.