Depression is thought to be caused by an imbalance of chemicals called neurotransmitters that send messages between nerve cells in your brain. Some of these chemicals, such as serotonin, help regulate mood. If these mood-influencing chemicals get out of balance, depression or other mood disorders can result. Experts have not yet identified why neurotransmitters become imbalanced. They believe a change can occur as a response to stress or illness, but a change may also occur with no obvious trigger.

There are several factors known to increase the chances that a young person may become depressed.

• Depression runs in families. Children and teens who have a parent with depression are 3 times more likely to develop depression than children with parents who are not depressed.² Experts believe that both inherited traits (genetics) as well as living with a parent who is depressed can cause depression.
• Depression in children and teens may be linked to stress, social problems, and unresolved family conflict. It can also be linked to traumatic events, such as violence, abuse, or neglect.
• Children or teens who have long-term or serious medical conditions, learning problems, or behavior problems are more likely to develop depression.
• Some medicines can trigger depression, such as steroids or narcotics for pain relief. As soon as the medicine is stopped, symptoms usually disappear.