Air pollution has now emerged as a significant contributor to stroke, along with high blood pressure, which has long been known as a primary risk factor. As the global burden of stroke continues to surge, there is an urgent need for improved prevention strategies to address this crisis.
Stroke is one of the most pressing global health concerns today, claiming millions of lives each year. According to a recent study published in The Lancet Neurology, the number of stroke-related deaths in 2021 reached a staggering 7.3 million, making stroke the third leading cause of death globally.
The study revealed alarming data about the growing prevalence of strokes, linking the increasing number of cases to air pollution, high blood pressure, and other modifiable risk factors.
In fact, over 11 million new stroke cases were reported in 2021, representing a 70% increase since 1990. Despite being a preventable and treatable condition, stroke continues to rise in prevalence, particularly in low- and middle-income countries.
This growing burden is not only attributed to population growth and ageing but also to increasing exposure to environmental and behavioral risk factors such as air pollution, poor diet, and physical inactivity.
Understanding Stroke: A Silent Killer
A stroke occurs when blood flow to a part of the brain is interrupted or significantly reduced, preventing brain tissue from receiving the oxygen and nutrients it needs to survive. Without prompt medical attention, brain cells begin to die within minutes, leading to potential brain damage, disability, or even death.
There are two main types of stroke: ischemic stroke, which is caused by a blockage in the arteries leading to the brain, and hemorrhagic stroke, which occurs when a blood vessel in the brain bursts. Both types are life-threatening and can cause long-term damage if not treated quickly.
Strokes are highly preventable, with 23 modifiable risk factors identified, including air pollution, excess body weight, high blood pressure, smoking, and physical inactivity. Unfortunately, the rising levels of air pollution and poor lifestyle choices have led to an increase in the incidence of strokes worldwide.
The Rising Burden of Stroke Worldwide
According to The Lancet Neurology study, the global burden of stroke has grown significantly over the past three decades. In 2021 alone, 11.9 million new stroke cases were reported, and 7.3 million people died from stroke-related complications. Stroke has become the third leading cause of death globally, following heart disease and cancer.
Read : Air Pollution Killed 135 Million People in Last Four Decades
This alarming increase is largely driven by population growth, ageing, and increasing exposure to risk factors such as air pollution and high blood pressure.
Between 1990 and 2021, the global stroke burden linked to high body mass index (BMI), high temperatures, high blood sugar, diet high in sugar-sweetened drinks, low physical activity, high systolic blood pressure, and diet low in omega-6 polyunsaturated fatty acids increased substantially. T
he number of years of healthy life lost to stroke also increased by 32%, making stroke the fourth leading cause of health loss globally.
The most concerning aspect of this growing burden is that strokes are largely preventable. With 84% of strokes linked to modifiable risk factors, there is a clear opportunity to curb this rising crisis through better prevention strategies and public health initiatives.
The Role of Air Pollution in Stroke Incidence
For the first time, the study revealed the significant role that air pollution plays in stroke incidence. The findings showed that particulate matter air pollution (specifically fine particulate matter known as PM2.5) is now one of the leading risk factors for stroke, on par with smoking.
Long-term exposure to air pollution has been linked to a higher risk of ischemic stroke and subarachnoid hemorrhage, a type of fatal brain bleed.
Particulate matter (PM) consists of tiny particles suspended in the air, which can penetrate deep into the lungs and enter the bloodstream, causing inflammation and oxidative stress in the body.
Over time, this can lead to the development of cardiovascular diseases, including stroke. The Lancet Neurology study highlighted the need for stronger air quality regulations and public health campaigns to reduce exposure to air pollution, particularly in urban areas where pollution levels are highest.
The connection between air pollution and stroke is particularly concerning in low- and middle-income countries, where rapid urbanization and industrialization have led to higher levels of air pollution.
These countries are disproportionately affected by stroke, accounting for over three-quarters of global cases. In many of these regions, access to healthcare and stroke prevention measures is limited, exacerbating the problem.
High Blood Pressure: A Major Risk Factor for Stroke
High blood pressure, also known as hypertension, remains the leading risk factor for stroke worldwide. Hypertension causes the arteries to become narrowed and hardened, making it more difficult for blood to flow through them.
This increases the likelihood of a blood clot forming and blocking the flow of blood to the brain, resulting in an ischemic stroke. In addition, high blood pressure can weaken blood vessels, making them more prone to bursting, which can lead to a hemorrhagic stroke.
The Lancet Neurology study found that the global burden of stroke linked to high systolic blood pressure increased by 7% between 1990 and 2021.
Despite significant advances in medical treatment and public health campaigns aimed at reducing blood pressure levels, the incidence of hypertension-related strokes has continued to rise, particularly in regions like Southeast Asia and Oceania.
One reason for this increase is the lack of awareness and treatment for high blood pressure in many parts of the world. In low- and middle-income countries, where healthcare resources are often limited, many people are unaware that they have high blood pressure and do not receive proper treatment. This has contributed to the growing number of stroke cases in these regions.
The Impact of Lifestyle Factors on Stroke Risk
In addition to air pollution and high blood pressure, several lifestyle factors play a major role in increasing the risk of stroke. These include high body mass index (BMI), high blood sugar, poor diet, and physical inactivity.
The Lancet Neurology study found that the global stroke burden linked to high BMI increased by 88% between 1990 and 2021, while the burden linked to high blood sugar increased by 32%.
A diet high in sugar-sweetened drinks and low in omega-6 polyunsaturated fatty acids also contributed to the rising number of stroke cases. A sedentary lifestyle, characterized by low physical activity, further increased the risk of stroke by 11%. These findings highlight the importance of adopting healthier lifestyles to reduce the risk of stroke and other cardiovascular diseases.
Population Growth and Ageing: Driving the Global Stroke Burden
While environmental and lifestyle factors play a significant role in stroke incidence, population growth and ageing are also major contributors to the global stroke burden.
As the world’s population continues to grow and age, the number of people at risk of stroke is increasing. Older adults are more likely to suffer from conditions like high blood pressure, diabetes, and heart disease, which increase the risk of stroke.
In many countries, the ageing population is expected to drive a continued rise in stroke cases over the coming decades. This demographic shift presents a significant challenge for healthcare systems, which must adapt to meet the growing demand for stroke prevention, treatment, and rehabilitation services.
The Need for Improved Prevention Strategies
The Lancet Neurology study underscores the urgent need for improved prevention strategies to address the global stroke burden. While age-standardized stroke rates have decreased globally since 1990, progress has stalled since 2015, particularly in Southeast Asia and Oceania. Researchers have called for new approaches to tackle modifiable risk factors such as air pollution, obesity, and unhealthy diets.
One of the key recommendations from the study is the need for stronger air quality regulations to reduce exposure to particulate matter pollution. Governments and public health organizations must also promote awareness campaigns to educate people about the risks of air pollution and encourage lifestyle changes that can reduce stroke risk.
In addition, there is a need for better access to healthcare and treatment for high blood pressure, particularly in low- and middle-income countries. This includes expanding access to affordable medications and regular blood pressure monitoring to help individuals manage their condition and reduce their risk of stroke.
Stroke is a preventable and treatable condition, yet it continues to claim millions of lives each year. The growing burden of stroke, driven by air pollution, high blood pressure, and other modifiable risk factors, demands urgent action.
As the world’s population continues to grow and age, the number of stroke cases is expected to rise, placing increasing pressure on healthcare systems globally.
By addressing the root causes of stroke, including air pollution and lifestyle factors, and implementing stronger prevention strategies, it is possible to reduce the incidence of stroke and improve health outcomes for millions of people around the world. The time to act is now, before this silent killer claims even more lives.
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