No, but there are risk groups, with women being more frequently affected than men. The risk groups include, for instance, people who are mostly over 50 and who have untreated blood pressure, diabetes, or atrial fibrillation. An exacerbating factor is that people in these risk groups often take too little exercise, are smokers, and are over-weight.
If, in addition, they have high cholesterol (i.e. their total cholesterol is permanently above 240 mg/dl), the risk of stroke is raised accordingly. By itself, the cholesterol value does not say a lot. The two types of cholesterol – “good” cholesterol, HDL and “bad” cholesterol, LDL – should be measured separately. If HDL is continuously below 50 mg/dl and LDL continuously above 130 mg/dl, the two values should be checked after a while to allow drug therapy, if necessary, to commence.
Does lifestyle play a role in stroke?
Available data would indicate that the modern lifestyle of people in the western industrialized nations has a major impact.
There are various types of strokes
Cerebral infarction is involved in 78 % of all stroke types. A distinction is made between blockage of an artery by a blood clot (thrombo-embolism) and blockage of a cerebral artery through narrowing as a result of atherosclerosis (hardening of the arteries).
The cause of these infarctions are thrombi which become lodged in he artery after having been transported there by the blood stream. The supply of blood and oxygen is then no longer adequate in certain regions of the brain. Ischaemia develops and can lead to cerebral infarction.
In 65% of patients who have suffered a cardiogenic embolic stroke the trigger was atrial fibrillation. In patients with atrial fibrillation, clots can form in the left atrium (see illustration).
Hardening of the arteries (atherosclerosis) is a less frequent cause of blockage in the brain, 14% of strokes are due to excessive bleeding (haemorrhaging) within or around the brain, which is mostly caused by high blood pressure, when readings are persistently above 140/90 mm Hg. The higher the blood pressure readings are, the greater is the risk. Blood escapes under high pressure from the burst vessels. The accumulation of blood presses on the neighbouring nerve cells, which can suffer damage.
Approximately 8% of strokes are due to dysfunction of the clotting system, haemorrhaging between the brain and the soft meninges, or vascular lesions, e.g. as a result of a whiplash injury or sudden violent movement of the head, though the latter are rather rare.
Atrial fibrillation as risk factor
Atrial fibrillation poses the greatest risk of cardiogenic embolic cerebral infarction, i.e. infarction which is triggered by the heart.
Although atrial fibrillation is not life-threatening, it must nevertheless be treated, firstly because of the long-term damage it can do to the heart, and secondly because of the potential for triggering a blockage in the brain, for instance, the kidneys or the leg arteries.
Due to the fact that the atria can no longer contract properly, if at all, blood becomes motionless in various parts of the left atrium. This is termed haemostasis, and may result in thrombus (clot) formation. If a thrombus is washed away and becomes lodged in the blood vessels around the brain, the supply of blood is disturbed, leading to cerebral infarction.
Where atrial fibrillation is persistent, life-long therapy with anticoagulants is required.
Anticoagulation is instituted with Marcumar®, Sintrom®, Warfarin in order to prolong the blood clotting time. The therapeutic range is between INR 2.0 and 3.0.