Excess weight during adolescence increases risk of stroke in women by age 55

Women who were overweight or obese at age 14 or 31 had an increased risk of ischemic stroke before age 55, according to a study published in Stroke. Ischemic stroke occurs when a vessel supplying blood to the brain becomes blocked, and is the most common type of stroke, accounting for about 87% of all cases.

A study from Finland found that women who were overweight at age 14 had an increased risk of stroke, even if they lost weight by age 31. Also, women who were overweight at age 31 had an increased risk of stroke, even if they were of normal weight at age 14. Men who were overweight at age 14 or 31 were not found to have an increased risk of ischemic stroke. However, obese men at age 31 had a higher risk of hemorrhagic stroke compared with obese women at age 31.

"Our findings suggest that excess weight may have long-term health consequences, even if it was temporary," said Ursula Mikkola, lead author of the study and a researcher at the University of Oulu in Finland. "Health care providers should be aware of overweight and obesity in young people and help them develop healthy eating and physical activity habits. However, conversations with adolescents and young adults about weight should be non-judgmental and stigmatizing."

To analyze the relationship between weight at different ages and the risk of stroke before age 55, the researchers used long-term data from participants in the Northern Finland Birth Cohort in 1966. In 1966, more than 12,000 pregnant women from two northern provinces of Finland were included in the study, and more than 10,000 of their offspring, now aged 50 years, were followed up consecutively.

The researchers used body mass index (BMI) to examine whether people who were overweight or obese at ages 14 or 31 had a different risk of early stroke compared with those who were not overweight or obese at those ages. Approximately 1 in 20 participants experienced an ischemic stroke or transient ischemic attack (TIA, or mini-stroke) over a mean follow-up period of almost 39 years after the 14-year assessment and almost 23 years after the 31-year assessment. The analysis was completed in 2020.

The impact of excess weight on the risk of stroke

• Women who were obese at age 14 were 87% more likely to have an early ischemic stroke or mini-stroke, while women who were obese at age 31 were 167% more likely to have a stroke compared with those who had normal weight
• Obese women at age 31 had nearly 3.5 times the risk of hemorrhagic stroke, and obese men at age 31 had more than 5.5 times the risk of hemorrhagic stroke.
• BMI measurements in earlier childhood or later adulthood did not affect the results.

"Living a healthy lifestyle (eating well, not smoking, sleeping well, controlling blood pressure, cholesterol and blood glucose levels, avoiding excess alcohol consumption and physical activity) can reduce the risk of stroke, even if you have excess weight in youth," added Mikkola.

The study has limitations because it is an analysis of medical data (an observational study) and cannot prove a cause-and-effect relationship between weight and the risk of early stroke. All participants were born in Finland, so the results may not apply to people in other countries.

"Stroke in young people is rare, so a difference of just a few cases can have a significant impact on risk estimates," Mikkola said. "Also, BMI is based only on a person's height and weight. Therefore, a high BMI can be a misleading way to determine obesity, especially in muscular people who may have little fat despite being heavier."

Researchers continue to study potential reasons for the lack of association between the increased risk of ischemic stroke in men and other risk factors in more detail.