The Greek philosopher, Epictetus, wrote long ago that nothing was so but that we think it so. For reactive, or situational depression, that fits. If there is a generational component, and your symptoms have been since childhood, to varying degrees, then it's organic and medication will be part of the healing. If the symptoms are mostly a result of ongoing events or life circumstances, then it's reactive, and the healing is on you. Through God's grace and your hard work, you can beat this depression.
Two tools for beating reactive depression. First, use the "as if" principle. When you are depressed, you don't feel like doing anything. Here comes moping, eating, laying around. Depression robs us of the activation process. If you don't feel like doing something, but in your heart what you are thinking of doing is good to do, then act "as if" you feel like doing it, and GET BUSY!
Second, activity is the antidote for reactive depression. When your heart gets above 120 beats/minute, your brain releases endorphins, nature's Prozac. Why buy this stuff when getting active releases the equivalent in your brain? It's hard to be active and depressed at the same time. Activity beats depression both because of the endorphins and also because the activity distracts you from the depression. Epictetus was right! Depressed? Nah. It's all in your head.
In Chapter Eight of Teachable Moments: Building Blocks of Christian Parenting, entitled Problems Can Be Solved, you will learn about these and other tools to help your child stay the course to adulthood.