Teens with slower performance on a test of "cognitive processing speed" are more likely to have depression and anxiety symptoms as adults, reports a new paper. Previous studies have shown that people with more severe depression have slower reaction times and other cognitive deficits. It has generally been assumed that this "psychomotor slowing" is a consequence of depression, rather than a risk factor for it. The new study suggests that slower processing speed may contribute to the development of mental health disorders -- possibly by leading to "increased stress and difficulties responding to adversity earlier in life."