Strokes can happen unexpectedly and without warning. Understanding the causes and risk factors for stroke can help identify who is at higher risk. Here are some of the main causes of unexpected strokes:
High blood pressure
High blood pressure, also called hypertension, is a major risk factor for stroke. It can damage blood vessels over time, causing them to narrow, weaken, and burst. High blood pressure often has no symptoms, so many people are unaware they have it until they suffer a stroke.
Atherosclerosis
Atherosclerosis occurs when fatty deposits called plaque build up inside the arteries. This narrows the arteries and makes it harder for blood to flow. If a piece of plaque breaks off, it can travel to the brain and block blood flow, triggering a stroke.
Atrial fibrillation
Atrial fibrillation (AFib) is a heart rhythm disorder that causes the upper chambers of the heart to beat irregularly. This allows blood clots to form, which can travel to the brain and cause a stroke. AFib often has no symptoms, so a stroke may be the first sign.
Blood clots
Blood clots that form in the veins, usually in the legs, can break off and travel to the brain. This type of clot is called a thrombus. Certain factors like smoking, obesity, and being inactive increase clot risk.
Patent foramen ovale
Patent foramen ovale (PFO) is a hole between the left and right upper chambers of the heart. Normally it closes after birth, but sometimes it remains open. This allows blood clots to bypass the lungs and go directly to the brain, potentially causing a stroke.
Carotid or cerebral atherosclerosis
Plaque buildup in the carotid arteries in the neck is called carotid atherosclerosis. This can limit blood flow to the brain and increase stroke risk. Cerebral atherosclerosis refers to plaque buildup in the arteries inside the brain.
Diabetes
Uncontrolled diabetes damages blood vessels and causes high blood pressure, increasing stroke risk. Diabetes also makes people more prone to atherosclerosis.
Sleep apnea
Sleep apnea causes people to periodically stop breathing while sleeping. This reduces oxygen levels and strains the cardiovascular system. Research shows sleep apnea increases stroke risk.
Smoking
Smoking damages blood vessel walls, speeds atherosclerosis, and increases blood pressure and heart rate. This all significantly raises stroke risk, especially for people who smoke heavily.
Excess alcohol
Drinking too much alcohol can raise blood pressure, triglycerides, and cholesterol levels. It may also trigger AFib and cardiomyopathy, further increasing stroke risk.
Illegal drugs
Using certain illicit drugs like cocaine and methamphetamines can dramatically increase stroke risk. They cause high blood pressure and damage blood vessels.
Heart problems
Conditions like valve defects, enlarged chambers, heart infection, and irregular rhythms like AFib can allow blood clots to form in the heart. These may travel to the brain, blocking blood flow and oxygen.
Previous stroke
Someone who has had a prior stroke is at higher risk of having another one. Aggressively managing risk factors is important for preventing repeat stroke.
Age and genetics
Risk of stroke increases with age, doubling every decade after age 55. Family history also plays a role. Having a parent or sibling with stroke raises your risk.
Ethnic background
Stroke risk varies between ethnic groups. For example, African Americans have a much higher rate of strokes compared to Caucasians. Reasons are likely genetic and socioeconomic.
Gender
Stroke occurs more often in men than women – until women reach menopause. Female hormones provide some protection before menopause. After menopause, women’s stroke risk is equal to men’s.
Conclusion
Many factors can contribute to an unexpected stroke. High blood pressure, heart problems, and atherosclerosis are some of the most common preventable causes. Others like age, gender, ethnicity, and family history cannot be changed. Knowing your personal risk profile is key to preventing a surprise stroke.