Smoking more than doubles the risk of unexplained strokes among adults under 50, according to new research from Keele University in the UK. The study reveals that heavy smokers face even greater danger, with those consuming more than a pack of cigarettes daily for 20 years experiencing over four times the risk compared to non-smokers.
"Our findings suggest that continued public health efforts around preventing smoking, especially heavy smoking, may be an important way to help reduce the number of strokes happening to young people," said lead researcher Phillip Ferdinand of Keele University.
The research focused specifically on cryptogenic strokes – those caused by blood flow blockages with no clear underlying cause. These unexplained strokes have been increasingly observed in younger populations, prompting researchers to investigate potential risk factors.
Smoking Intensity Dramatically Increases Risk
The study compared medical records of 546 people aged 18 to 49 who suffered unexplained strokes against 546 age and sex-matched individuals without stroke history. Results showed 33% of smokers had experienced an unexplained stroke, compared to just 15% of non-smokers.
The risk varied significantly based on smoking intensity, gender, and age:
- People smoking 11-20 cigarettes daily showed a 64% increased stroke risk
- Those smoking more than 40 cigarettes daily faced 5.2 times the risk
- Male smokers had three times higher risk than non-smokers
- Men smoking more than a pack daily for 20 years faced nearly seven times the risk
- Adults aged 45-49 had nearly five times the risk compared to non-smokers
"Recent research has shown an increase in younger people having these unexplained strokes, so it is important to evaluate any potential links. Our study found that smoking may be a key factor," Ferdinand explained.
Mechanisms Behind Smoking-Related Stroke Risk
The World Stroke Organization identifies multiple pathways through which tobacco smoke increases stroke risk. Cigarette smoke contains thousands of harmful chemicals affecting the circulatory system, including carbon monoxide, which lowers blood oxygen levels, and nicotine, which raises blood pressure.
Smoking also negatively impacts cholesterol levels and increases the risk of arterial hardening, creating conditions favorable for stroke development.
Non-Traditional Risk Factors Also Significant
A complementary study from Helsinki University Hospital in Finland identified several non-traditional risk factors that can more than double stroke odds in people under 50. These include migraines with aura, blood clots in veins, kidney or liver disease, and cancer.
"We were surprised by the role of non-traditional risk factors, especially migraine headaches, which seems to be one of the leading risk factors in the development of strokes in younger adults," said Dr. Jukka Putaala, head of the stroke unit at Helsinki University Hospital.
The Finnish research analyzed data from over 1,000 Europeans aged 18-49, comparing those who suffered unexplained ischemic strokes with healthy individuals. They found that each additional non-traditional risk factor increased stroke risk by 70%, while each traditional risk factor (like high blood pressure or diabetes) increased risk by 41%.
Implications for Stroke Prevention
These findings highlight the importance of comprehensive stroke risk assessment in younger adults, particularly those who smoke. The research suggests that smoking cessation could significantly reduce unexplained stroke incidence in this population.
Public health experts emphasize that recognizing both traditional and non-traditional risk factors could transform approaches to screening and patient education throughout their lives.
The Keele University study appears in the journal Neurology, while the Helsinki University Hospital research was published in Stroke.
