John David Spence

Effects of the intestinal microbiome on atherosclerosis He reported with colleagues in 2018 that patients with carotid atherosclerosis not explained by traditional risk factors had higher blood levels of toxic metabolites produced by intestinal bacteria from foods such as red meat and egg yolk. His group also found that blood levels of those toxic products are elevated with even moderate impairment of kidney function, such as seen in elderly patients. This has important implications for diet, and offers the possibility of an entirely new way of treating atherosclerosis: repopulation of the intestinal microbiome.

Physiologically individualized therapy for resistant hypertension. Reported in 2017 that in patients in three hypertension clinics in Africa, measuring plasma renin activity and aldosterone markedly improved blood pressure control, but permitting selection of the treatment that is appropriate to that patient, by identifying the physiological cause of the hypertension.

Appropriate carotid endarterectomy: Showed in 2005 () that with intensive medical therapy most patients with asymptomatic carotid stenosis cannot benefit from endarterectomy or stenting, and that the very small proportion (10%) who may benefit can be identified by microembolus detection on transcranial Doppler. Showed in 2010 () that the proportion who could benefit had declined with more intensive therapy to less than 5%. SPARC's work was confirmed in 2010 by an international multicenter study, the ACES study. Dr. Spence led a study in the Canadian Atherosclerosis Imaging Network, on histological validation of imaging features of vulnerable plaque that will also serve to identify high-risk carotid plaques.

Ultrasound measurement of plaque: Beginning in 1990, Dr. Spence pioneered the use of carotid plaque measurement (as opposed to intima-media thickness) for research and for management of patients with carotid artery disease. (.). This has evolved to the use of 3-D plaque volume measurements for evaluation of new therapies. The effect of drug therapies on carotid plaque volume can now be evaluated in a very cost-effective way.

Effects of antihypertensive drugs on blood velocity and arterial flow disturbances 1976, 1980, 1995: these studies showed that antihypertensive drugs have different effects on blood velocity and arterial flow disturbances, which have implications for how effective they are at fighting the buildup of arterial plaque. (.)

John David Spence CM (born November 10, 1944) is a Canadian medical doctor, medical researcher and professor at the University of Western Ontario. Along with his affiliation with the University of Western Ontario (where he teaches Clinical Neurological Science) he is affiliated with the London Health Sciences Centre's University Hospital (where he has set up and runs stroke prevention clinics) and the Robarts Research Institute, one of Canada's leading medical research organizations. He is a recognized expert in stroke prevention and stroke prevention research and has over 500 peer-reviewed publications since 1970. He has delivered more than 600 lectures in 38 countries to physicians around the world. In 2015, he received the Research Excellence Award from the Canadian Society for Atherosclerosis, Thrombosis and Vascular Biology. In 2019, he was appointed a Member of the Order of Canada.