[Health Tip] Does Stroke Risk Increase When It Gets Colder? 'Daily Temperature Range' Is More Important

Citizens dressed in thick clothing are hurrying along the streets of Gwanghwamun, Seoul. Photo by Hyunmin Kim kimhyun81@

[Asia Economy Reporter Chunhee Lee] When the weather gets colder in winter, the inevitable topic that arises is the increased risk of stroke due to the cold weather. However, in academia, the hypothesis that daily temperature variation plays a more significant role in the onset of cerebral infarction than seasonal factors is more widely accepted.

Stroke refers to conditions such as cerebral infarction, where blood vessels supplying blood to the brain are blocked, or cerebral hemorrhage, where blood vessels leading to the brain rupture causing bleeding. It is one of the top three causes of death in South Korea and ranks first in mortality among single diseases. If treatment for stroke is delayed, it can lead to death as well as severe aftereffects such as physical paralysis and consciousness disorders. Furthermore, it is a serious disease that causes mental, physical, and economic difficulties for the patient’s family as well.

As temperatures drop, concerns about stroke increase. Theoretically, lower temperatures can cause blood vessels to constrict and blood pressure to rise, and at extremely low temperatures, blood becomes more viscous, making blood clots (thrombi) more likely to form. However, Professor Choi Hyeyeon of the Department of Neurology at Gangdong Kyung Hee University Hospital explained, "Various studies have been conducted both domestically and internationally on this topic, and based on the research results so far, there is a greater consensus that daily temperature variation influences cerebral infarction onset more than temperature or season."

In fact, one study found that for every 1℃ increase in daily temperature variation, the risk of acute stroke increased by 2.4%, and by 2.7% in those aged 65 and older. However, stroke incidence rates were similar across all four seasons, and temperature differences had less impact on hemorrhagic stroke. When reviewing other studies, the relationship between stroke and high or low temperatures was inconsistent; some reported increased stroke risk and mortality at both high and low temperatures, while others concluded there was no relationship.

The exact reason why daily temperature variation affects cerebrovascular diseases, especially cerebral infarction, is not yet clear. However, hypotheses include that sudden temperature changes may increase hemodynamic changes and cardiovascular burden, or that they may induce respiratory infections by disrupting immune function and promoting the secretion of inflammatory mediators, thereby indirectly increasing the incidence of acute stroke.

Choi Hye-yeon, Professor of Neurology at Gangdong Kyung Hee University Hospital
Photo by Gangdong Kyung Hee University Hospital

Hearing this, people often think that because daily temperature variation increases in winter, they should stay warm indoors when it is cold. However, Professor Choi explained, "Staying indoors without moving is not the right answer." Reduced physical activity is also not good for stroke risk or prognosis. He advised, "Rather than overemphasizing uncontrollable factors like temperature, it is much more important to focus on controllable risk factors to prevent stroke."

If you have risk factors for stroke such as hypertension, heart disease, or diabetes, you should strive to prevent stroke through regular exercise, dietary management, and appropriate treatment. In daily life, avoid alcohol and smoking, prevent overwork, and maintain moderate exercise. To prevent hypertension, diabetes, and obesity, reducing sugar and salt intake, limiting animal fat consumption, and maintaining a regular lifestyle can help prevent stroke.