Pick up the book Against Depression It describes new research that proves the physical changes that depression causes on the brain and is very easy to read.
Some of the new research is that Depression can be diagnosed by autopsy. The brain is made up of several different types of cells. Depressives (those with depression) have less of a certain type of cell in the frontal lobe causing them to be more susceptible to enviromental factors. The book describes is much better than I ever could.
There was more research that demonstrated how a part of the brain is actually damaged by the condition of depression. The longer you have it, the more damge there is.
Depression is not that much diffrent than heart failure. There is a change in the body when you get heart failure. You can tell heart failure on tests, but for the most part you can't tell you have it untill an attack happens. At that point you have to change parts of your life and possibly take medications. The medications may be short term, or long term, but there is no way to tell that in the beginging when the attack happens.
Heart conditions and heart failure are accepted medical conditions because there has been more research done on that area. Development on Depression is more difficult because the measurements taken are harder to achieve. It took years to come up with the research that was there and more info is just coming in.
Sometimes guys need the hard facts and not emotional stories to show them that something is real. Buy him the book.
May your day be filled with laughter and love.