Can strokes be prevented?

Yes, strokes can be (partly) prevented. Strokes are caused by a failure in cerebral blood circulation. We classify them into two types: ischemic and hemorrhagic.

An ischemic stroke is caused by an occlusion (blockage) of the passage of blood. Generally, there’s thrombus that clogs a cerebral artery. This triggers a series of pathophysiological mechanisms that lead to the death of cells that should be receiving this blood circulation. Approximately 80% of strokes are ischemic — this is the most frequent kind.

Hemorrhagic strokes, meanwhile, account for the remaining 20% of cases. They occur due to bleeding in the brain, following the rupture of a blood vessel in the cerebral artery. In this case, there are also some pathophysiological mechanisms that — as occurs with ischemic strokes — end up causing the death of the brain cells that should be receiving blood.

A stroke is a disabling disease that, in most cases, affects adults. However, on occasion, there are also pediatric strokes. But, in adults, strokes are the principal cause of acquired disabilities.

As I noted earlier, strokes, in part, can be prevented. When we talk about ischemic strokes, there are two main groups of causes. The first are related to cardiovascular and cerebrovascular risk factors — what are known as “shared vascular risk factors” — including hypertension, diabetes, dyslipidemia (the alteration of levels of fat, cholesterol and triglycerides in the blood), smoking and, according to certain studies, obesity. These vascular risk factors cause blood vessels to harden or accumulate atheromatous plaque, which essentially cause the vessels to close, or an embolism to occur (when a part of that atheromatous plaque detaches and obstructs an artery). This is the most common cause of ischemic strokes.

The second-most frequent cause of these types of strokes is when they have cardioembolic origins. That is, when heart disease causes an embolism, which subsequently travels through the bloodstream to the brain and causes an ischemic stroke.

In the first case that I discuss, if certain pathologies are prevented — hypertension, diabetes, cholesterol, smoking, obesity — the possible occurrence of a stroke is prevented at the same time. In the case of cardioembolic ischemic stroke, however, what’s required is the prevention of embolisms caused by heart disease. Basically, this happens when there’s an arrhythmia (an irregular heartbeat). If the arrhythmia is treated with appropriate drugs — most often anticoagulants — you can prevent an embolism and, therefore, also prevent a possible stroke.

As for hemorrhagic strokes, vascular risk factors — such as hypertension — do play a role. But there are other causes, such as the accumulation of abnormal proteins. For instance, cerebral amyloid angiopathy (CAA) is a condition in which proteins build up in the arteries in the brain. Something like this is more difficult to prevent. However, the treatment of hypertension can prevent both ischemic strokes and hemorrhagic strokes.

A stroke is a very serious pathology. In many developed countries, before the pandemic, it was the leading cause of death among women and the third among men. Strokes are also a major cause of disabilities: the leading cause of acquired disabilities, as well as the second-leading cause of vascular dementia.

While strokes can occur in children, this is very rare. In general, the risk of suffering a stroke increases with age.

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