John David Spence (born November 10, 1944) is a

Canadian Canadians () are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of their being ''C ...

medical doctor A physician, medical practitioner (British English), medical doctor, or simply doctor is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through the study, diagnosis, prognosis ...

, medical researcher and Professor Emeritus at the

University of Western Ontario The University of Western Ontario (UWO; branded as Western University) is a Public university, public research university in London, Ontario, Canada. The main campus is located on of land, surrounded by residential neighbourhoods and the Thame ...

. He is affiliated with the University of Western Ontario (where he taught Clinical Neurological Science) and the

Robarts Research Institute The Robarts Research Institute is a medical research institute at the University of Western Ontario, as part of the Schulich School of Medicine and Dentistry. Staff scientists work to investigate a range of diseases including heart disease, strok ...

, one of Canada's leading medical research organizations. Before his retirement from clinical practice in July 2022, he was also affiliated with the London Health Sciences Centre's

University Hospital A teaching hospital or university hospital is a hospital or medical center that provides medical education and training to future and current health professionals. Teaching hospitals are almost always affiliated with one or more universities a ...

(where he set up and ran stroke prevention clinics). He is a recognized expert in stroke prevention and stroke prevention research, with more than 600 peer-reviewed publications since 1970. He delivered more than 600 lectures on stroke prevention in 42 countries. In 2015, he received th
Research Excellence Award
from th
Canadian Society for Atherosclerosis, Thrombosis and Vascular Biology
. In 2019, he was appointed a Member of the Order of Canada, and in 2020 he received the William Feinberg Award from the American Heart Association for excellence in clinical stroke research

Dr. Spence is the director of th
Stroke Prevention & Atherosclerosis Research Centre (SPARC)
a unit of the

. With Maria Dicicco, RVT, he pioneered the measurement of total plaque area (TPA) in a patient's carotid artery using

ultrasound Ultrasound is sound with frequency, frequencies greater than 20 Hertz, kilohertz. This frequency is the approximate upper audible hearing range, limit of human hearing in healthy young adults. The physical principles of acoustic waves apply ...

technology. The ability to measure TPA gives doctors the ability to treat, and measure the change in, the amount of plaque in a patient's

arteries An artery () is a blood vessel in humans and most other animals that takes oxygenated blood away from the heart in the systemic circulation to one or more parts of the body. Exceptions that carry deoxygenated blood are the pulmonary arteries in ...

and has given researchers the ability to measure the effectiveness of new drug treatment therapies for stroke prevention. in high-risk patients with narrowing of the carotid arteries, the process of "Treating Arteries" was associated with a >80% reduction in the 2-year risk of strokes and heart attacks. Dr. Spence is recognized as
The Father of Total Plaque Area Measurement
and the importance of TPA measurement is that, in Dr Spence's words, "We can now treat arteries instead of just treating

risk factors In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often ...

Spence - Key Research Discoveries

Cerebral Cerebral may refer to: * Of or relating to the brain * Cerebrum, the largest and uppermost part of the brain * Cerebral cortex, the outer layer of the cerebrum * Retroflex consonant, also referred to as a cerebral consonant, a type of consonant so ...

consequences of

hypertension Hypertension, also known as high blood pressure, is a Chronic condition, long-term Disease, medical condition in which the blood pressure in the artery, arteries is persistently elevated. High blood pressure usually does not cause symptoms i ...

: treating high blood pressure prevents only arteriolar strokes. (.) This research led to the understanding that the effects of therapies, designed to reduce hypertension, on blood pressure need to be distinguished from other effects on

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...

. 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. (.) Effects of grapefruit juice on drug

metabolism Metabolism (, from ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cellular processes; the co ...

: The discovery with Drs. David Bailey and Malcolm Arnold, that grapefruit juice markedly increases blood levels of a number of drugs that have low

bioavailability In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...

because of gut wall first-pass metabolism by

CYP3A4 Cytochrome P450 3A4 (abbreviated CYP3A4) () is an important enzyme in the body, mainly found in the liver and in the intestine, which in humans is encoded by ''CYP3A4'' gene. It organic redox reaction, oxidizes small foreign organic molecules ( ...

made a major contribution to the understanding of

pharmacokinetics Pharmacokinetics (from Ancient Greek ''pharmakon'' "drug" and ''kinetikos'' "moving, putting in motion"; see chemical kinetics), sometimes abbreviated as PK, is a branch of pharmacology dedicated to describing how the body affects a specific su ...

, and has opened up a new field of

pharmacology Pharmacology is the science of drugs and medications, including a substance's origin, composition, pharmacokinetics, pharmacodynamics, therapeutic use, and toxicology. More specifically, it is the study of the interactions that occur betwee ...

. (). 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. Development of quantitative traits for human atherosclerosis: Spence developed a number of quantitative traits that will advance the search for new

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

tic causes of atherosclerosis, and thus new therapeutic targets and new therapies for atherosclerosis. These are unexplained atherosclerosis and its progression, unexplained protection from atherosclerosis and unexplained regression of atherosclerosis. (;.) Appropriate

carotid endarterectomy Carotid endarterectomy is a surgical procedure used to reduce the risk of stroke from carotid artery stenosis (narrowing the internal carotid artery). In an endarterectomy, the surgeon opens the artery and removes the plaque. The plaque forms ...

: Showed in 2005 () that with intensive medical therapy most patients with asymptomatic carotid stenosis cannot benefit from endarterectomy or

stenting In medicine, a stent is a tube usually constructed of a metallic alloy or a polymer. It is inserted into the lumen (hollow space) of an anatomic vessel or duct to keep the passageway open. Stenting refers to the placement of a stent. The wor ...

, and that the very small proportion (10%) who may benefit can be identified b
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 th
Canadian Atherosclerosis Imaging Network
, on histological validation of imaging features of vulnerable plaque that will also serve to identify high-risk carotid plaques. 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. 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.

Special Projects

# Member of the

set up by the Ministry of Health and the Heart and Stroke Foundation. # Member of th

which is recognized in the U.S. Centers of Excellence program in their work for heart attack prevention and eradication. # National stroke prevention program of the Argentina health organization training Argentinean physicians in vascular prevention.

Education and Training

Ridley College Ridley College may refer to * Ridley College (Melbourne), Victoria, Australia * Ridley College (Ontario), Canada See also * Ridley Hall, Cambridge, Cambridgeshire, England, UK * * Ridley (disambiguation) {{schooldis ...

. # M.D.

. # Clinical Pharmacology training at the Cardiovascular Research Institute of the

University of California at San Francisco The University of California, San Francisco (UCSF) is a public land-grant research university in San Francisco, California, United States. It is part of the University of California system and is dedicated entirely to health science and life s ...

. # M.B.A. from the

University of Toronto The University of Toronto (UToronto or U of T) is a public university, public research university whose main campus is located on the grounds that surround Queen's Park (Toronto), Queen's Park in Toronto, Ontario, Canada. It was founded by ...

. # Trained with Henry J. M. Barnett at University Hospital in London Ontario. Dr. Barnett is a leading stroke researcher who pioneered the use of aspirin in stroke prevention therapy.

Personal life

Spence is the great-grandson of David Spence (Canadian Politician) and trained with Henry J. M. Barnett

References

External links

Stroke Prevention & Atherosclerosis Research Centre (SPARC)

Society for Heart Attack Prevention and Eradication (SHAPE)

VASCULAR RISK FOUNDATION

Order of Canada
{{DEFAULTSORT:Spence, John David 1944 births Living people Canadian cardiologists Canadian medical researchers Academic staff of the University of Western Ontario Members of the Order of Canada