This study about possible relationships between racism and mental health is an interesting one. It has the usual problem of one-shot studies: It can't tell us which came first, and because of that it can't really prove causality:
Fifth-graders who feel they've been mistreated because of their skin color are much more likely than classmates without such feelings to have symptoms of mental disorders, especially depression, a study suggests.
There is evidence that racial discrimination increases the odds that adolescents and adults will develop mental health problems, but this is the first study to examine a possible link in children of varied races, says Tumaini Coker, the study co-author and a RAND Corp. researcher and UCLA pediatrician.
It does not prove that discrimination caused the emotional problems, because unlike studies of older people, these children weren't followed over time. It's possible that prejudice harms children's mental health, but it is also possible that troubled kids prompt more discriminatory remarks from peers or that children with emotional problems perceive more bias, says study leader Mark Schuster, a Harvard pediatrician and pediatrics chief at Children's Hospital Boston.
It would be even harder to do a similar study on sexism and its possible correlation with mental health problems, because sexism is much more diffuse and because it may begin inside the family rather than just outside it.