Adolescents can have mental illnesses that interfere with the way they think, act, and feel.  Mental illnesses can lead to school failure, family conflict, drug abuse, behavioral problems or violence if untreated.  Untreated mental illnesses can be very expensive for families, communities and health care systems.  Many adolescents have mental health problems that interfere with their normal development and functioning.

The most common mental disorders that affect adolescents include: Attention Deficit Hyperactivity Disorder (ADHD) Eating Disorders (Anorexia, Bulimia) Anxiety Disorders Conduct Disorder Depression Oppositional Defiant Disorder Schizophrenia

Mental health disorders in adolescents are usually caused by biological or environmental factors.  Examples of biological causes are genetics, chemical imbalances in the body, or damage to the central nervous system, such as a head injury.  Many environmental factors also influence the likelihood of developing a mental illness.  Such environmental factors include:

• Exposure to environmental toxins (for example, high levels of lead)
• Exposure to violence (for example, witnessing or being the victim of physical or sexual abuse, drive-by shootings, muggings or other disasters)
• Stress related to chronic poverty, discrimination or other serious hardship
• The loss of significant people through death, divorce or broken relationships