World Stroke Day is on 29th October.
Stroke is a major global public health problem. According to the Global Burden of Diseases (GBD) report stroke is the second leading cause of death worldwide with nearly 5.87 million stroke deaths in 2010. It is one of the leading cause of chronic disability all over the world. As per the recent population-based studies in India, the incidence of stroke is found to be around 120 – 145 people per a lakh of individuals.
It is a medical emergency that hinders or blocks the blood supply to a part of the brain. This causes the brain cells to start dying, leading to stroke and impacting the bodily functions controlled by that specific part of the brain.
Risk factors of stroke
There are certain factors that increase your risk of stroke. According to the National Heart, Lung and Blood Institute of the USA, more the risk factors a person carries the higher is the risk of having a stroke. However, the fact that around 50% of stroke risk can be prevented through control of modifiable risk factors and lifestyle changes is not emphasized enough. Prevention of these factors plays a crucial role in lowering the morbidity and mortality associated with stroke. The common modifiable risk factors of stroke include:
1. Diet: Studies have shown that an unhealthy diet can increase the risk of stroke. A diet that is high in saturated fats, processed grains, salt, and simple sugars was associated with an increase in stroke incidence. However, a diet that is loaded with fruits and vegetable, whole grains, legumes, and fish, was associated with a decreased stroke incidence. A Cochrane review in 2013 suggested that adherence to a healthy diet can decrease the lifetime risk of stroke by nearly 20%.
The current guidelines for stroke prevention include dietary recommendations to increase the content of vegetables and fruits, as well as a diet with low-fat dairy products with low content of saturated fat, in addition to reduced intake of sodium and increased intake of potassium.
2. Inactive lifestyle: Lack of exercise or leading a sedentary lifestyle is known to have a lifelong inverse relationship with stroke. This is particularly of concern for young people where unhealthy lifestyle was seen as a modifiable risk factors of stroke. People who are highly active (around 2 hours of daily vigorous activity) are estimated to have a 25-30% lower risk of stroke as compared to inactive people.
Moreover, exercise reduces blood pressure, decreases body weight, and improves other risk factors of stroke, thereby lowering the overall risk. Moderate to intense exercise at least 40 minutes per day for three to four times a week is considered as an effective and useful recommendation for primary stroke prevention.
3. Smoking: Smoking is an independent stroke risk factor, which increases the risk of stroke by around 50%. Tobacco not only damages the blood vessel but also increases your blood pressure, which raises the risk of stroke. The risk increases proportionally with the number of cigarettes smoked per day and passive smoking also increases the risk of ischemic stroke.
Smoking cessation is an effective measure to reduce stroke risk. Among smokers, cessation leads to a decrease in stroke risk to levels similar to non-smokers by 5 years. Several options are available for effective smoking cessation such as counseling and pharmacologic interventions including nicotine replacement. Studies have proved that medical counseling and nicotine replacement therapies have found to increase the success of smoking cessation by around 70%.
4. Alcohol consumption: It goes without saying that heavy alcohol consumption is a strong risk factor of stroke. However, studies have reported that drinking more than two drinks per day can put you at risk of stroke. Alcohol consumption is directly linked with hemorrhagic stroke, even small amounts of alcohol. Moreover, heavy alcohol consumption is linked to hypertension and poor blood pressure control, which is also one of the risk factors of stroke.
To lower your risk of stroke, it is recommended that men should limit to 2 drinks per day and women to not more than a drink per day.
5. Obesity: Being overweight and obese can predispose you to numerous health complications including stroke. However, the risk of stroke-related disabilities is higher for old people. It is reported that the risk of stroke-related mortality increases significantly if the body mass index (BMI) is greater than 25 kg/m2. People with greater abdominal obesity were twice likely to get a stroke.
Current guidelines recommend weight reduction for stroke prevention along with daily physical activity. There are no studies that prove weight loss to lower the risk of stroke, however losing weight can improve the risk of diabetes and hypertension, which are the major modifiable risk factors of stroke.
6. Hypertension: High blood pressure or hypertension is one of the most prevalent modifiable risk factors of stroke. It contributes to around 60% of all strokes. Studies have reported that an increase of every 20 mm Hg of systolic blood pressure or 10 mm Hg of diastolic pressure against the normal can double the risk of mortality due to ischemic heart disease and stroke.
However, keeping the blood pressure in control or reduction of 5-6 mm Hg blood pressure can significantly lower your risk of the first stroke. A 10 mm Hg reduction in systolic or a 5 mm Hg reduction in diastolic blood pressure can result in around 40% lower risk of stroke death.
7. Diabetes: Uncontrolled diabetes is a known risk factor of heart disease, which in turn puts you at risk of stroke. Moreover, if you are obese or have a heart condition, the risk increases further.
It is estimated that the risk of stroke in a person with diabetes is around five times higher than those with normal blood glucose level. Also, diabetics tend to have an increased incidence of stroke at a younger age. According to the American Diabetes Association, the normal fasting plasma glucose level is less than 100 mg/dl.
8. Atrial fibrillation: Atrial fibrillation is a condition that causes irregular heartbeat and poor blood flow. It is often asymptomatic and undetected, which is the reason it is often underestimated. However, it is known to be important and independent risk factors of stroke. It increases the risk of stroke risk about 5 times across all age groups. Atrial fibrillation is the underlying cause of around 15% of all strokes and is known to carry a higher risk of mortality and disability.
9. High cholesterol levels: People with a low level of high-density lipoprotein (HDL or good) cholesterol have been found to be at higher risk of stroke. There is an increased risk for ischemic stroke with increased total cholesterol, and a decreased risk for ischemic stroke with elevated HDL cholesterol. This is because, cholesterol can up the risk of arterial blockage due to plaque deposition and impair blood flow, which in turn can lead to coronary heart disease. Thus there is a direct link between high total cholesterol level, coronary artery disease, and stroke.
10. Stress: It is reported that psychosocial stress, which includes marital stress, abuse, health problems or financial problems, is independently associated with an increased risk of stroke. Stress can impact both men and women similarly and can lead to fatal stroke in around 22% of people suffering from stress.
A 2015 study titled “Epidemiology and prevention of stroke: a worldwide perspective” found that occupational stress associated with job strain increased the risk of stroke by twofold. Job stress and depression were associated with coronary heart disease, mortality, and stroke. Stress is also associated with unhealthy behaviors such as inactivity, change in diet and increased smoking, which are known risk factors of stroke.
In addition to these modifiable risk factors of stroke, there are few non-modifiable factors that can put you at risk of the condition. These include a family history of stroke, age, and race/ethnicity.
(The article is reviewed by Dr. Lalit Kanodia, General Physician)
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