He did not understand it well at all. Even today, clinical depression (and many other mental health conditions) isn't well understood by the general public. There is still, despite all the efforts made to combat it, a stigma attached to mental health problems and treatment. Think of that TV commercial in which the young woman is walking around with a masking device saying "I tried to hide my depression." It's an ad for a certain medication. If he had been older at the time, I don't think it would have mattered. The state of knowledge at the time was the same regardless of age. Today, he can understand better, but not necessarily because he is older; the knowledge and treatment methods have improved.