Smokers are 41 percent more likely to suffer from clinical depression than nonsmokers, according to a study of more than 8,500 people.

Science Daily reported April 25 that the researchers led by Almudena Sanchez-Villegas of the University of Navarra in Spain also found that subjects who had quit smoking for at least a decade prior to the study were less likely to be depressed than lifelong nonsmokers.

Researchers at the University of Navarra, the University of Las Palmas de Gran Canaria, and the Harvard School of Public Health relied on self-reports and mental-health assessments for their findings. The study included college graduates with an average age of 42.

The study also found that smoking increases tend to reduce physical activity.