World Stroke Day: Doctor Explains How Winter Increases Your Stroke Risk

As temperatures drop, the risk of stroke rises, and this is something doctors and researchers have observed across the globe. Several studies, including those published in The Lancet and Stroke, have shown a notable spike in ischemic stroke cases during winter months, especially when average temperatures fall below 13 degrees Celsius. According to Dr Manoj Khanal, Director, Neurosciences, Max Super Speciality Hospital, Shalimar Bagh, cold weather affects the cardiovascular and circulatory systems in multiple ways, including raising blood pressure, thickening blood, and even increasing clot formation. "Compared with warmer temperatures, the low-temperature group shows a significantly higher proportion of patients with hypertension and large artery atherosclerotic stroke," he notes.

With World Stroke Day 2025 focusing on prevention, experts are urging greater awareness of how seasonal changes can affect brain health. Understanding this connection is particularly crucial in northern India, where winter temperatures can dip sharply, triggering physiological stress responses that heighten the risk of both ischemic and haemorrhagic strokes.

How Cold Temperatures Increase Stroke Risk

1. Blood Pressure Rises As Blood Vessels Constrict

"When it's cold, blood vessels constrict to conserve body heat, which increases blood pressure and places extra strain on the cardiovascular system," explains Dr Khanal. According to the World Health Organization (WHO), hypertension is the leading modifiable risk factor for stroke, and winter months often see a spike in uncontrolled cases.

2. Thicker Blood And Higher Clot Risk

"Cold temperatures slightly thicken the blood, making it more prone to clotting," says Dr Khanal. These clots can block blood flow to the brain, causing an ischemic stroke. A 2023 study in the Journal of the American Heart Association (JAHA) found that lower ambient temperatures are linked to increased blood viscosity and platelet reactivity, which elevate the risk of clot formation.

3. Reduced Physical Activity And Weight Gain

During winter, people tend to move less and eat more calorie-dense foods. "Reduced physical activity contributes to weight gain, higher cholesterol, and elevated blood pressure-all of which increase stroke risk," says Dr Khanal. The American Stroke Association notes that even moderate activity, such as brisk walking for 30 minutes a day, can reduce stroke risk by up to 25%.

4. Dehydration In Cold Weather

"People often feel less thirsty in winter, leading to dehydration," Dr Khanal points out. "This makes blood more viscous and prone to clotting." A European Journal of Preventive Cardiology study (2021) found that dehydration increases haemoconcentration and platelet aggregation, two key mechanisms behind stroke formation.

5. Overexertion In Cold Weather

Strenuous activity in cold weather, such as snow shovelling or outdoor labour, can sharply raise heart rate and blood pressure. "Any sudden physical exertion in cold conditions can lead to cardiovascular strain and elevate stroke risk," warns Dr Khanal.

The National Institute of Neurological Disorders and Stroke (NINDS) notes that such exertion can trigger strokes in individuals with underlying heart or artery disease.

6. Seasonal Infections and Inflammation

"Winter also brings flu and respiratory infections," Dr Khanal adds. "Inflammation from infections can damage blood vessels and worsen hypertension and heart disease, leading to increased stroke risk." Research published in Neurology journal (2022) links respiratory infections to a threefold increase in stroke risk within the first three days of infection.

Prevention: How To Lower Stroke Risk In Cold Weather

"Prevention in winter requires extra vigilance," Dr Khanal emphasizes. He recommends the following steps:

• Stay Warm: "Wear layers and keep your core temperature stable to prevent blood vessel constriction."
• Stay Active: Engage in moderate indoor exercises; avoid overexertion.
• Stay Hydrated: Drink adequate fluids, even if you don't feel thirsty.
• Manage Co-Morbidities: Keep blood pressure, cholesterol, and diabetes under control.
• Limit Alcohol And Avoid Smoking: "Alcohol dilates blood vessels temporarily but strains the heart; smoking constricts vessels and raises blood pressure."
• Get Flu Vaccinated: "Vaccination reduces respiratory infections and indirectly lowers stroke risk by preventing blood vessel inflammation." A 2024 BMJ study found that flu vaccination was associated with a 12% lower stroke risk in adults over 50.

Both cold and hot extremes can raise stroke risk, but the impact of cold temperatures tends to last longer, according to multiple studies. Low temperatures are associated not only with ischemic stroke but also with hypertension, haemorrhagic events, and vascular inflammation.

Dr Khanal cautions, "If you experience sudden symptoms like loss of balance, facial weakness, arm or leg numbness, or slurred speech during cold weather, rush to the nearest stroke-ready hospital for immediate care. Early intervention is crucial for recovery."

Disclaimer: This content, including advice, provides generic information only. It is in no way a substitute for a qualified medical opinion. Always consult a specialist or your own doctor for more information. NDTV does not claim responsibility for this information.