Children can be diagnosed with depression although they do not necessarily have the same signs and symptoms as adults. A depressed child can be sad and have the adult hallmark symptoms of helplessness, hopelessness and worthlessness.
Depressed children, however, are often irritable, impossible to please, and moody, swinging from great sadness to sudden anger. Depression is most likely due to an inherited predisposition to a chemical imbalance in the brain. Effective treatments include medication and cognitive behavior therapy.
Real Life Stories

Alex, l0-years-old, lives with his mother and grandmother. His parents separated when he was six. Alex's teacher reports that he is in danger of failing, that he becomes preoccupied, often staring out the window, and seldom finishes his work. Alex has stated that the other children in the class are much smarter than he is. He seldom attends Boy Scout meetings or plays baseball, which he used to enjoy. When he gets home each afternoon, he watches television and eats all the cookies he can find. He usually telephones his mother to make sure she's all right and then goes to bed until his mother comes home. "I don't have any reason to stay up; nothing good is going to happen," he said.

Cheryl usually went to school and to her part-time job, and then came home and played with her cats, rather than go out with her two best friends, as she used to. Looking back, her mother realized that Cheryl hadn't gone to the movies or shopping for the past month and seemed to have lost weight. Then her mother found a bottle of sleeping pills on Cheryl's dresser.

Both Alex and Cheryl have been diagnosed with depression.
What are the symptoms?

All children feel sad sometimes. However, some children are sorrowful beyond the range of normal sadness. In general, for children to be diagnosed with Major Depressive Disorder, they will have experienced depressive symptoms constantly for at least two weeks to such a degree that it interferes with their lives. According to the Diagnostic and Statistical Manual - IV, children will also have had at least five of the following symptoms.
depressed or irritable mood
difficulty concentrating
irritability and anger
fatigue
feelings of worthlessness
sleep problems
appetite problems
social withdrawal
restlessness or slowing down
decreased interest or pleasure in activities
thoughts of death

There are two basic types of depression: major depression which lasts at least two weeks, and the milder but chronic dysthymic disorder, in which a long-standing depressed mood that lasts for a year or longer seems to characterize the child's temperament or personality.

Children who have major depression can actually be quite "up" at times, but when they are down, they're very "down." Depressed children can have trouble paying attention, feel tired, feel mad, cry, stay in their room, stop participating in favorite activities, think about death, or do risky things and not know why. Teens often exhibit symptoms of dramatic sadness more similar to those found in adults.

Some children don't realize that they are depressed. They may be under stress at school, be upset about something that happened with their friends, sleep or eat more than usual, or just want to be alone because they don't have fun when they are out. They are often bored by everything. Children who are depressed can't just "snap out of it" and are not being weak.

The children and teens most at risk are those who have difficulty seeing a solution to their problems. Sometimes they feel killing themselves is the only way to stop their pain. Children and teens who talk about suicide or death should be taken seriously; they are not necessarily just looking for attention. When a child talks about suicide, a professional should be consulted. As with most problems, parents and professionals are concerned with duration, frequency and intensity.