Smoking, particularly excessive consumption, is linked to some strokes of unknown origin in young adults, mainly in men and individuals between 45 and 49 years old, according to a study published in the online edition of the official journal of the American Academy of Neurology, Neurology.
An unknown cause stroke, known as cryptogenic stroke, is a type of ischemic stroke caused by a blockage of blood flow, where it is unclear what caused the blockage. The symptoms include weakness, difficulty speaking, and vision problems. Strokes can be fatal, and most occur after the age of 65.
"Although smoking has long been associated with ischemic stroke, little is known about how it affects those under 50, especially those who experience an unexplained stroke," says Phillip Ferdinand, from the University of Keele (United Kingdom) and a member of the American Academy of Neurology. "Recent research has shown an increase in the number of young people experiencing these unexplained strokes, so it is important to assess any possible relationship. Our study found that smoking would be a key factor."
Every year in our country, between 110,000 and 120,000 people suffer a stroke. Every six or seven minutes, a stroke occurs in Spain. According to the document Stroke: Action Plan in Europe 2018-2030, from the Stroke Alliance for Europe (SAFE), by 2035, Europe is expected to see an increase in the number of strokes (34%), stroke-related deaths (45%), and survivors with disabilities (25%).
25% of strokes in Spanish patients correspond to the study's situation. This percentage rises to 50% in young individuals, necessitating more thorough studies as the causes are very heterogeneous, as stated in the Health document Stroke Strategy of the National Health System
Pablo Irimia, a consultant at the Neurology Department of the University of Navarra Clinic (CUN), mentioned that although it is true that it is strongly associated with age - and we are living longer - around 15-20% of patients are under 50 years old. "It is important to emphasize that this condition can affect individuals at any age, even children."
Tobacco kills approximately 54,000 people a year in Spain, and 27.5% of those deaths (over 14,000 in absolute numbers) are due to cardiovascular diseases, including diabetes. These are findings from a study reported by the Spanish Society of Cardiology (SEC) and the Spanish Heart Foundation (FEC).
In our country, despite the observed reduction in tobacco consumption in the latest Health survey, Estudes, one in four Spaniards still smokes daily. In 2024, 25.8% of Spaniards aged 15 to 64 report daily smoking, compared to 35.1% in 2001. Although smoking rates have increased among women, it is still higher in men, 40.9% versus 32.7%. This difference is even more pronounced in the age group highlighted in the study: 31.9% and 26.9%. And seven out of ten still opt for traditional cigarettes.
How did they measure the risk of stroke and tobacco in the study?
For the study, researchers analyzed 546 individuals aged 18 to 49 who had experienced a stroke of unknown origin. They were matched by age and gender with an equal number of individuals who had not had a stroke.
Participants answered questions about their smoking habits, alcohol consumption, educational level, physical inactivity, and other health issues. Researchers reviewed the responses to determine which factors could be related to the unexplained stroke.
In this regard, they found that individuals who had experienced an unexplained stroke were more likely to smoke. Of those who had suffered a cryptogenic stroke, 33% were smokers, compared to 15% of those who had not experienced it.
After adjusting for factors that could affect stroke risk, such as education level, alcohol consumption, and blood pressure, researchers observed that smokers were more than twice as likely to experience an unexplained stroke compared to non-smokers. They also found that the risks were higher in male participants, who had over three times the odds, and among those aged 45 to 49, with nearly four times the risk.
The intensity of tobacco consumption, i.e., how many cigarettes a person smoked per day, was also a key factor in the analysis. Individuals who smoked the equivalent of more than 20 packs per year had over four times the risk of experiencing an unexplained stroke compared to non-smokers. This risk was significantly higher in men, with almost seven times more risk, and in the age range of 45 to 49 years, with nearly five times more risk.
"Our findings suggest that ongoing public health efforts regarding smoking prevention, especially excessive habits, can be an important way to help reduce the number of strokes in young individuals," Ferdinand states.
A limitation of the study is that it mainly focused on individuals of white European descent, so the results may not be the same for other populations. The study was supported by the Helsinki and Uusimaa Hospital District, the Academy of Finland, the University of Helsinki, and Sahlgrenska University Hospital.