A stroke occurs when the blood supply to a part of the brain is interrupted. This interruption happens due to a blocked or burst blood vessel, depriving brain cells of oxygen and nutrients. Without prompt treatment, brain cells can die within minutes, leading to lasting damage.
The General Age Trend of Stroke Occurrence
While a stroke can affect individuals at any point in life, the likelihood of experiencing one significantly increases with advancing age. The average age for stroke occurrence is around 74 years. Studies show a clear rise in stroke incidence after age 60, with the highest rates observed in people in their 90s.
Recent data indicate a shift in stroke demographics. While overall stroke incidence may be decreasing in older adults, it is either rising or remaining stable in younger populations. For instance, the proportion of strokes in individuals under 55 years increased from 12.9% in 1993/1994 to 18.6% in 2005 in one study. Similarly, from 2011 to 2022, stroke prevalence increased among adults aged 18-44 years by 14.6%.
Strokes in Older Adults
The majority of stroke cases occur in older adults due to age-related physiological changes and the accumulation of various health conditions. The most common type of stroke in this demographic is ischemic stroke, accounting for about 87% of all cases, which occurs when a blood vessel supplying the brain becomes blocked. Conditions like atherosclerosis, where fatty plaque builds up in arteries, are prevalent in older individuals and can lead to these blockages.
Atrial fibrillation (AF), an irregular heart rhythm, is a significant contributor to stroke risk in older adults. AF can cause blood clots to form in the heart, which may then travel to the brain and cause an embolic stroke. Hypertension, or high blood pressure, is the most common risk factor for stroke in older adults, frequently leading to both ischemic and hemorrhagic strokes. Additionally, long-standing diabetes and other metabolic disorders can damage blood vessels over time, increasing susceptibility to stroke in this age group.
Strokes in Younger Individuals
Strokes can occur in younger adults (under 50 years) and even in children. The causes of stroke in younger individuals are often distinct from those in older adults and can be more challenging to identify. One notable cause is arterial dissection, a tear in the wall of an artery in the neck or head, a leading cause of ischemic stroke in young and middle-aged adults.
Another condition linked to stroke in younger people is a patent foramen ovale (PFO), a small hole between the heart’s upper chambers that did not close properly after birth. This opening can allow blood clots to pass from one side of the heart to the other and travel to the brain. Genetic conditions also play a role, including sickle cell disease, which increases stroke risk in children due to misshapen red blood cells that can block blood vessels. Other genetic disorders like CADASIL and Fabry disease are also associated with stroke in younger populations.
Certain infections, autoimmune diseases, and the use of oral contraceptives, especially when combined with other risk factors like smoking, can increase stroke risk in younger individuals. Diagnosing strokes in this age group can be difficult because symptoms may be atypical, and the possibility of stroke is often not the first consideration for healthcare providers.
Understanding Age-Related Risk Factors
Stroke risk factors, such as high blood pressure, high cholesterol, diabetes, obesity, and smoking, contribute to stroke across all ages. The cumulative effect of these factors over time increases an individual’s susceptibility to stroke as they age. For instance, chronic uncontrolled high blood pressure gradually damages blood vessels, making them more prone to blockages or ruptures.
While these traditional risk factors are increasingly seen in younger stroke patients, particularly due to rising rates of obesity and diabetes, their long-term presence often leads to more severe vascular damage in older adults. Managing these modifiable risk factors through lifestyle choices, such as regular exercise and a healthy diet, and medical interventions is important at every stage of life to reduce the overall lifetime risk of stroke.