Cold wave has once again tightened its grip across North and Central India due to a western disturbance triggering widespread rain and snowfall in many regions. Chilly weather not only makes you slow and lazy, but also increase risk of life-threatening conditions. Especially for people with heart and blood pressure issues, low temperatures can be deadly as they pose a heightened risk of brain stroke.
A study published in the Journal Epidemiology suggests that stroke occurrence rises as mercury plummets. Even a moderate decrease in temperature can raise the risk of ischemic stroke, as per the study. Who is most at risk of a brain stroke in cold weather, and what exactly can be done to prevent it? Financial Express.com spoke to Fortis Gurgaon Neurologist Dr Sahil Kohli to get a better understanding.
What happens to the body in extremely cold conditions
When temperatures drop, the body quietly switches into survival mode. It works harder to preserve heat, protect vital organs, and keep blood flowing where it’s needed most. But these protective responses come at a cost. For some people, especially those with existing risk factors, cold weather can place unexpected strain on the heart and blood vessels.
“Cold weather places multiple physiological stresses on the body that can trigger strokes, especially in vulnerable people. To conserve heat the body constricts blood vessels. This raises blood pressure. Also, the heart must pump harder against narrowed vessels, increasing the risk of vessel rupture or clot formation,” says Dr Kohli. “Exposure to cold also leads to release of stress hormones which can elevate heart rate and blood pressure.”
Why does cold weather increase the risk of brain strokes?
In cold conditions, blood becomes thicker and flows more slowly through tiny vessels. This makes it harder for oxygen to reach vital tissues, especially the brain. Over time, reduced circulation raises the risk of ischemia and clot-related strokes.
“Cold weather can lead to reduced oxygen delivery, thickening blood and reducing microcirculation, thereby increasing ischemic stroke risk. There are higher chances of both ischemic stroke (clots) and hemorrhagic stroke (bleeding) during cold waves,” warns the Fortis neurologist.
Deadly effects of cold waves
Cold weather can lead to sudden blood pressure spikes. In people with hypertension, these sudden spikes can lead to strokes, heart attacks, or ruptured vessel, particularly during early morning cold exposure. “Cold-induced vasoconstriction can raise blood pressure by 10–30 mmHg. Sudden BP surges can rupture weakened brain vessels,” says Dr Kohli.
During cold days, the body loses more fluid through respiration while thirst sensation declines. This can cause mild but persistent dehydration. At the same time, cold reduces plasma volume, making blood denser and slower-flowing. This increased viscosity heightens the risk of clot formation, especially in coronary and cerebral arteries.
Cold weather may reduce plasma volume. Dehydration is common in winter due to reduced thirst. Thicker blood flows slowly which can lead to higher clot risk,” says the expert.
Cold temperatures stimulate platelet activation and aggregation, while levels of clotting proteins such as fibrinogen rise. Together, these changes tilt the body toward a pro-thrombotic state, increasing susceptibility to heart attacks, ischemic strokes, and pulmonary embolism, particularly in older adults and those with existing cardiovascular disease, according to Dr Kohli.
During intense winters, people tend to stay indoors and their mobility is often restricted. This can be dangerous as physical inactivity slows venous blood flow, especially in the legs, allowing blood to pool and clot more easily.
This can increase the risk of deep vein thrombosis and cardiac events, compounding the circulatory strain already imposed by cold exposure, says the expert.
Who are the high-risk groups for cold-related strokes?
As per Dr Kohli, high-risk populations include older adults or people above 60 years, those with hypertension, people with diabetes, heart disease patients, people with previous stroke or TIA, smokers, high cholesterol, chronic kidney disease or those living alone or in poorly heated homes. “Risk rises further if medications are missed, alcohol intake increases, or cold exposure is sudden,” says the expert.
Warning signs families should watch for in winter months
Use the FAST rule, but also watch for subtle winter-specific symptoms:
Classic stroke warning signs:
F – Face drooping
A – Arm or leg weakness/numbness
S – Speech difficulty
T – Time to call emergency services
Additional red flags in cold weather, as per Dr Kohli include sudden confusion or drowsiness, severe headache after exposure to cold, loss of balance or coordination, blurred or double vision, sudden vomiting with high BP, chest discomfort or any sudden neurological symptoms.
Daily precautions to reduce stroke risk during a cold wave
Now that we know who all need to follow additional precautions during cold wave to prevent health emergencies, it’s time to undestand preventive measures. Here’s what Dr Kohli suggests:
It is strong suggested to keep indoor temperatures stable as extremely low temperatures can lead to health emergencies.
It is advisable to dress up in layers, protecting your head, neck, and hands from cold exposure.
Avoid early morning walks and step out of home only when it’s sunny.
If you struggle with hypertension, blood pressure management is the key. Monitoring blood pressure regularly in winter is recommended. Most importantly, do not skip or delay blood pressure medications and consult a doctor if readings rise persistently.
Hydrate yourself well during winter as you may not always feel thirsty. Apart from water, try warm fluids like soups and herbal teas to help maintain circulation.
Do not strain yourself by doing intense exercise during extreme winter months. Experts suggest gentle indoor exercises.
Avoid sitting for long durations. Get up every 30-45 minutes to stay active.