A stroke occurs when blood flow to a part of the brain is disrupted, causing brain cells to die from a lack of oxygen and nutrients. The vast majority of strokes, about 87%, are ischemic, meaning a blood clot blocks a blood vessel within the brain. The less common type is a hemorrhagic stroke, which happens when a blood vessel ruptures and bleeds into the surrounding brain tissue. While age is the most significant statistical factor influencing stroke risk, these events can occur at any point in the human lifespan, from infancy to extreme old age.
The Increasing Risk After Age 55
Aging is the strongest non-modifiable risk factor for experiencing a stroke, with the incidence accelerating rapidly after middle age. The risk of stroke doubles approximately every ten years following the age of 55. This sharp increase means that roughly three-quarters of all strokes happen in individuals aged 65 and older.
The primary reason for this age-related acceleration is the cumulative effect of traditional, modifiable risk factors over decades. Chronic hypertension, or high blood pressure, damages the lining of blood vessels, contributing to the buildup of plaque in a condition called atherosclerosis. This narrowing and hardening of arteries increases the likelihood of a clot forming and causing an ischemic stroke.
Conditions like diabetes and atrial fibrillation (AFib) also become much more prevalent with age, significantly elevating stroke risk. AFib, an irregular heart rhythm, allows blood to pool in the heart chambers, which can lead to the formation of blood clots that may travel to the brain. Poorly controlled blood sugar from diabetes contributes to vascular damage and inflammation, accelerating atherosclerosis.
Causes of Stroke in Young Adults
Stroke in young adults (ages 18 to 50) represents a smaller percentage of the total but often has different underlying causes than in older populations. While traditional factors like hypertension and obesity contribute, non-traditional causes are frequently identified because atherosclerosis is less pronounced in this age group.
One mechanism is arterial dissection, a tear in the inner layer of an artery wall, often in the neck (carotid or vertebral arteries). These tears can be spontaneous or result from minor trauma, such as aggressive neck manipulation, and they can lead to clot formation. Paradoxical embolism is another unique cause, where a clot travels from the venous system to the arterial system through a structural heart defect, such as a Patent Foramen Ovale (PFO).
A PFO is a small opening between the upper chambers of the heart that failed to close after birth, allowing blood clots to bypass the lungs’ filtering system. Young adults are also more likely to have strokes linked to genetic clotting disorders (thrombophilia), which increase the blood’s tendency to clot. Substance abuse, particularly the use of cocaine or amphetamines, can cause severe, sudden spikes in blood pressure that may result in either ischemic or hemorrhagic strokes.
Understanding Pediatric Stroke
Stroke can occur in infants and children, though it is a relatively rare event. Pediatric stroke is classified into two main categories: perinatal stroke (28th week of pregnancy to 28 days after birth) and childhood stroke (28 days to 18 years of age). The causes are often distinct from those found in older adults, frequently involving congenital or hematological conditions.
Congenital heart disease is a leading cause, as structural heart defects can increase the risk of blood clots traveling to the brain. Blood disorders, notably sickle cell disease, cause red blood cells to become sticky, leading to blockages in the brain’s blood vessels and a significantly increased risk of ischemic stroke. Vascular malformations, like arteriovenous malformations (AVMs), are also a cause, as these abnormally formed blood vessels can rupture and cause a hemorrhagic stroke.
Infections like varicella zoster virus (chickenpox) can cause inflammation and narrowing of the arteries in the brain, a condition called arteriopathy. Diagnosis is often delayed because the symptoms may be subtle or mistaken for other childhood conditions, such as seizures or developmental issues. Pediatric stroke remains a significant cause of neurological disability in children.
Recognizing the Signs of Stroke at Any Age
Recognizing the warning signs immediately is important for a positive outcome. The most widely used method for rapid identification is the F.A.S.T. acronym, which helps people remember the three most common physical signs and the appropriate response.
F stands for Face drooping, observed if one side of the person’s face droops or feels numb when they try to smile. A is for Arm weakness, typically seen if the person cannot raise both arms equally or if one arm drifts downward when held out. S is for Speech difficulty, which can manifest as slurred speech, trouble finding words, or an inability to understand simple instructions.
The T stands for Time to call emergency services immediately, even if the symptoms disappear quickly. This urgency is encapsulated in the phrase “Time is Brain,” reflecting that millions of brain cells die every minute a stroke goes untreated. Prompt medical attention, ideally within the first few hours, allows doctors to administer clot-busting medications or perform procedures that can minimize permanent damage.
While the F.A.S.T. signs are common in all age groups, symptoms in young children can sometimes be more generalized, making recognition difficult. In infants, symptoms may include sudden seizures that affect only one side of the body, or an unexplained, sudden loss of previously mastered skills.