Most depressive symptoms exhibited by adolescents are attributed to the normal stress of adolescence or misdiagnosed as a mental disorder and/or stage they are going through. Depression in youth can manifest in different forms. Symptoms that resemble attention-deficit/hyperactivity disorder may form. The adolescent may have an angry, hostile disposition and not know why, and even substance abuse may occur (Bhatia, 2007). These symptoms, and many others, could be the cause of a primary or secondary depressive mood disorder. To diagnose primary depressive mood disorder, depression from medical causes has to be ruled out. If it cannot be, the condition is considered depressive mood disorder secondary to medical conditions (Bhatia, 2007). Diagnosis of minor depression requires the presence of two out of nine symptoms for major depression (Bhatia, 2007). To properly treat any diagnosis of depression, the etiology of the depressive mood disorder must also be investigated.
One of the most common predictors of adolescent depression is a family history of depression. Behavior genetic studies on youth have found depression to be moderately heritable starting in adolescence at about age 11 and continuing on into adulthood (Hankin, 2006). Hankin (2006) also states that depressive symptoms are heritable in children younger than 11 years of age through a shared common family environment, but not genetic factors. Not only have studies been conducted on the effect a family history of depression has on an adolescent, but have also shown the effect maternal depression has on adolescent cognition. Garber (2001) found that maternal depression is associated with the negative cognitions in their offspring. Youth with a history of depression on their mother's side were found to have lower self-esteem, lower perceived self worth, and higher levels of depressive thinking than children of medically ill and well mothers.