It's normal for teenagers to have shifts in their moods, to be irritable and to be sad sometimes. However, if a teen is suffering from depression, his entire life is affected. He'll have a hard time succeeding in school, getting along with his parents and making and keeping friends. Treatment for depression includes therapy, medication and lifestyle changes.

Major Depression

Teens suffering from major depression exhibit symptoms for at least two weeks. Symptoms of major depression include feelings of sadness, worthlessness and hopelessness, thoughts of suicide, difficulty concentrating, fatigue, insomnia, significant weight loss or gain and loss of pleasure. A teenager who's experiencing major depression may inflict self-harm, such as cutting herself. She might partake in risky behaviors, such as using illegal drugs and having unprotected sex, because she doesn't care about herself. A telltale sign that a teen is depressed is her sudden lack of caring about her appearance. She might not shower for a few days, stop wearing makeup and wear the same outfit to school four days in a row.

Dysthymic Disorder

For an adolescent to receive a diagnosis of dysthymic disorder, he'll need to have had a depressed mood for more than half the days of a year as well as two more symptoms of depression. Teens who have experienced a major depressive episode or manic episode do not fit into this category. Dysthymic disorder is a milder form of major depression. Usually, an adolescent with this disorder does not have suicidal thoughts and can function more than a teen with major depression.

Manic Depression

Manic depression, also known as bipolar disorder, is a mood disorder that is characterized by major depressive episodes and manic episodes. If a teen is having a manic episode, she will have an elevated or irritable mood for at least one week along with other symptoms, such as grandiosity, little need for sleep, racing thoughts, difficulty concentrating and increased involvement in risk taking behaviors.

Adjustment Disorder with Depressed Mood

When a teen experiences a significant life event, such as moving to a new state or starting a new school, it might be difficult for her to adjust. She might react to the life event by experiencing symptoms of depression, such as hopelessness and tearfulness. If the depressed mood occurs within three months of the event and does not meet the criteria for major depression, it is usually categorized as adjustment disorder with depressed mood.

Postpartum Depression

Teen girls can experience symptoms of major depression after giving birth. If the symptoms occur within one month of having a baby, it will be diagnosed as postpartum depression instead of major depression. However, it'll be treated similar to major depression.