Working long hours for more than 10 years may be associated with stroke, especially for people under the age of 50, according to research by the American Heart Association.

The study was published in the association’s journal Stroke, and found that people who worked long hours had a higher risk of stroke, especially if they worked those hours for more than 10 years.

The long work hours were defined in the study as working more than 10 hours for at least 50 days of the year. Part-time workers and those who suffered strokes before working long hours were excluded.

The data came from a French population-based study group that started in 2012 and looked at age, sex, smoking and work hours from 143,592 participants.

The study found that 1,224 of the participants suffered strokes; 29%, or 42,542, reported working long hours; 10%, or 14,481, reported working long hours for 10 years or more; participants who worked long hours had a 29% greater risk of stroke, and those working long hours for 10 years or more had a 45% greater risk of stroke.

The study’s author said that the association between 10 years of long hours and having a stroke appeared strong for people under 50.

Previous studies noted a smaller effect of long work hours among business owners, CEOs, professionals, managers and farmers. Researchers said that it might be because those workers have greater “decision latitude” than others. Previous studies have also suggested that irregular shifts, night work and job strain may be responsible for unhealthy work conditions.