People who leave school early with low grades could be more likely to kill themselves. Researchers from the Karolinska Institutet and the Swedish National Board of Health and Welfare used some of the huge amounts of data which the Swedish state records about its citizens. They looked at the school-leaving grades - at age 16 - of almost 900,000 people born between 1972 and 1981 and tracked who later went on to kill themselves between the ages of 25 and 34. They found that those with the highest grades had the lowest risk of committing suicide while those with the lowest grades had a risk three times higher than average. The researchers took into account the educational level of the sample's parents, whether their parents were on benefit or single, the age of their mothers, their parents' mental health and drug use and whether they had been adopted.
You can find out more about this research here.