So what. 1+1=2, if you take away all knowledge about how things are chosen, you take away all subjectivity in regards to what makes those decisions turn out the way they do as well. So with throwing out creationism, you throw out subjectivity as well, and that results in depression.
Maybe the depression is caused from feeling that they have to choose between creationism and evolution. I can believe in a Creator, and still believe in the theory of evolution. One doesn't need to be an atheist, in order to believe in evolution.
edit to add, that the article is vague as to what's causing it, but it could simply mean change in and of itself is causing it. Transitioning into college life that first year, can be daunting, and overwhelming.