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Chest pain (squeezing, pressure, heaviness, tightening, or aching across the chest) due to an insufficient supply of oxygen-rich blood to the heart muscle. In most cases, the lack of blood supply to the heart is due to a narrowing of the coronary arteries as a result of coronary heart disease.


One of the two types of blood supply pipes through which blood flows around the body. Arteries are the ones through which blood carrying oxygen, picked up in the lungs, supplies oxygen to the muscles and other tissues throughout the body. (Veins bring the blood back to the heart and to the lungs, where some of the body's waste products, such as carbon dioxide, are expelled as we breathe out).


Aspirin is a medicine which is usually used to relieve mild to moderate pain; reduce fever, redness, and swelling (doses of at least 300mg are used for pain relief). Aspirin is also used to reduce the risk of a second heart attack or stroke because it has blood thinning properties (i.e. it reduces the ability of blood to clot). Low doses of aspirin (75 to 150mg daily) are sufficient to have a blood thinning effect. In ASCEND the dose of aspirin being used is 100mg daily.

Cardiovascular disease

A term used to mean the 'furring up' or narrowing of arteries anywhere in the body: in the heart (coronary heart disease), in the brain (cerebrovascular disease) or in the main arteries or legs (peripheral vascular disease).

Cerebrovascular disease

Term used to describe the 'furring up' or narrowing of the arteries leading to or in the brain. A sudden blockage of these arteries causes a stroke (see below).

Clinical trial

A research study conducted with people, usually to evaluate the effect of a treatment or drug. Each trial is designed to answer specific scientific questions and to find better ways to treat people with particular diseases.

Cognitive Function

Cognitive function (sometimes called brain power) is ability in any mental process including memory, problem solving and language.  Cognitive function can be measured in research studies using a set of standard questions asked in the clinic or over the telephone, or using online web-based cognitive function tests.

Coronary arteries

The arteries (see above) which carry oxygen-rich blood to the heart muscle.

Coronary heart disease

Coronary heart disease is the term used when the coronary arteries become narrowed or 'furred up' by a fatty coating on the inside of the artery. This can result in angina and, sometimes, a heart attack.


A medical condition in which the body cannot control the level of sugar in the blood. This is caused either by a lack of insulin (a hormone in the body which helps control sugar levels in the blood) or resistance to the effect of insulin. In either case this leads to the incorrect regulation of sugar levels in the blood. There are 2 main types of diabetes:

  • Type 1 - a form of diabetes which usually starts during childhood, adolescence or early adulthood (also known as insulin-dependent diabetes). It is caused when cells of the immune system attack and kill specific cells in the pancreas (the organ in the body that produces insulin), so that the pancreas makes too little or no insulin at all. The exact cause is unknown, but genetic factors seem to play an important role.
  • Type 2 - a form of diabetes that usually starts in middle-age (also known as adult-onset or insulin-resistant diabetes). The cells of the pancreas produce insulin, but the body is unable to use it effectively because the cells of the body are resistant to the action of insulin. This type of diabetes is normally treated by changes in diet, weight control, exercise and oral hypoglycaemic agents (drugs taken by mouth which lower blood sugar levels).

Double-blind study

A kind of clinical study where neither the study participants nor the doctors looking after them know which treatment an individual is taking. This design helps to ensure that the results of the study are reliable and accurate (since neither the doctor nor the patient can affect the observed results with their personal bias about the treatment being studied).


Relating to the stomach and intestine.

Heart attack (or myocardial infarction)

This happens when the supply of oxygen-rich blood flowing through one or more of the coronary arteries to the heart muscle is cut off (which is why a heart attack is also sometimes called a coronary). Oxygen is needed to power all our muscles, including the all-important muscle of the heart. If the supply of oxygen is severely reduced, the muscle of the heart indicates this with pain and can then malfunction or cut out.

Heart disease

There are several different types of heart disease. Coronary heart disease is caused by narrowing or 'furring up' of the arteries which supply the heart. In another type of heart disease the heart muscle itself can be abnormal which can cause the heart to pump less effectively. This is sometimes as a result of an enlarged heart muscle which can be caused by high blood pressure.

Omega-3 fatty acids (fish oils)

Omega-3 fatty acids are oils high in unsaturated fats, extracted from the bodies of fish or fish parts, especially the livers. These are polyunsaturated fats (ie with more than one "double-bond" in their side chains). The site of the first of these "double-bonds" whether in the "3" position (as in omega -3 fatty acids) or in the "6" position (as in sunflower oil) determines some of the properties of the oils. As a general rule, unsaturated fats are liquid at room temperature. Olive oil is also an unsaturated oil, but it has just one "double-bond", and so is sometimes known as a mono-unsaturated fat.


A placebo is a dummy tablet or capsule which contains no active medication. In ASCEND the placebo tablets and capsules look exactly the same as the active medication.

Random allocation (or randomised)

The treatment a participant receives in ASCEND (either aspirin or placebo and either omega-3 fatty acid or placebo) is randomly allocated by computer. This is a bit like tossing a coin. Each participant will have a 50% chance of receiving active aspirin and a 50% chance of receiving the placebo ("dummy") tablets, and also a 50% chance of receiving active omega-3 fatty acids and a 50% chance of receiving "dummy" capsules.


This illness, usually involving loss of movement or feeling on one side of the body, is caused either by the blood supply in the arteries to the brain being blocked (called an "occlusive" or "ischaemic" stroke) or by a bleed into the brain (called a "haemorrhagic" stroke" - haemorrhage just means bleed).

Transient ischaemic attack (sometimes called a mini-stroke or TIA)

A short-lived illness (which starts suddenly and normally clears up within 24 hours) of temporary impairment to the brain, resulting in temporary paralysis, numbness and speech difficulty. This is caused by a lack of oxygen supply to the brain due to an obstruction to the arterial blood supply or inadequate blood flow. The loss of blood supply to the brain is most often caused by a clot that forms in a blood vessel within the brain, however it can also result from a clot that forms elsewhere in the body, dislodges from that location, and travels to lodge in an artery of the brain.

Vascular disease

Vascular disease means a disease affecting any of the arteries or veins in the body. Heart disease and stroke are examples of vascular diseases.


An anticoagulant (blood thinning) medicine, used to prevent or slow down the formation of blood clots which can block blood vessels.