How was depression solved in The Giver?

In The Giver, people who are depressed apply for release, which means death. For example, the Receiver of Memories before Jonas, a girl named Rosemary, was given pain, loneliness, and sadness by the Giver in the process of her training. He also gave her the memory of a child who was taken from its parents. She experienced trauma, poverty, and hunger in the course of her five-week training. The Giver sensed that Rosemary was sad, and he tried to give her an experience of happiness to alleviate her pain. However, that effort came too late, and Rosemary asked the Chief Elder for release (and it was given to her). After Rosemary was released, all her painful memories flooded back into the community, overwhelming people. However, the rules Jonas are given before he begins to train make it clear that he cannot ask for release while training as a Receiver of Memories.