Depression is a major problem for adolescents in America, according to the Mayo Clinic “Depression affects 20% of adolescents in the United States” (“Diseases and Conditions”). This is an alarming number of teenagers suffering from this deadly disease. Many people assume that a change in a teenager's behavior is another phase that will fade away in a month or so; however, there is more to it than many people think. Adolescent depression is as old as time itself and can be defined as “…a strong mood involving sadness, discouragement, hopelessness, or hopelessness that lasts for weeks, months, or longer” (“Depression”). It often passes without warning because the teenage years are difficult times with all the changes happening in their lives and the stress imposed by schools, jobs, parents and coaches. In the past, medical professionals didn't think teenagers were capable of feeling the kind of pain caused by depression. New research and studies show that life experience is only a small factor in depression. Depression is caused by the imbalance of chemicals in a person's brain. Someone who is 12 can be just as depressed as someone who is 40. Adolescent depression can also affect a person's adult life. Many adults who suffer from depression also experienced some type of chronic depression as teenagers. Teenage depression can cause problems not only in the present, but also in the future. Depression often goes undiagnosed in teenagers because of all the chaos going on in their lives. Adolescence is considered a time of change, so it is not easy to distinguish between common changes and those caused by depression. It is also a time known for rebellion and estrangement from parents, making it difficult to even t...... middle of paper ......ks CitedBringing Teen Depression to Light." CBS Evening News. CBS. March 30, 2009. Television. Web. February 3, 2014Cobain, Beverly When Nothing Matters Anymore Minneapolis, MN: Free Spirit Publishing Inc., 1998. Print. Children's Health. nd Web. February 3, 2014 "Diseases and Conditions: Adolescent Depression." Mayo Clinic. Mayo Foundation for Medical Education and Research, November 7, 2012. Web February 24, 2013. Koplewicz, Harold “More than Moody: Recognizing and Treating Adolescent Depression.” 12 (2002): Print.Kersting, K. “Adolescent Depression May Affect Adult Happiness.” American Psychological Association, 03 September 2003. Web 10 February 2014. “All Careers in Psychology” The Psychology Career Center, n.d. Web. 2013.