Prevention is always preferred to treatment after the fact. Louis Pasteur commented that “when meditating over a disease, I never think of finding a remedy for it, but instead, a means of preventing it.”1 During the past half century, doctors have pursued several familiar strategies to prevent ischaemic strokes: (1) control medical disorders such as hypertension, diabetes, obesity, hyperlipidaemia, and behaviours such as smoking, excess alcohol intake, lack of exercise—known risk factors for ischaemic stroke; (2) Prescribe one treatment, a panacea. for all patients with symptomatic brain ischaemia depending on the then fashionable treatment. Vasodilators, warfarin, heparin, carotid surgery, surgical bypass, and aspirin all have had periods of favour; and (3) choose treatment according to time oriented categorisation of neurological symptoms and signs such as transient ischaemic attacks, progressing stroke, reversible ischaemic neurological deficits, and “completed” strokes.

Among these approaches only risk factor control is a viable strategy. Brain …