Suicide is one of the major causes of death in the U.S. In the adolescent populations, suicide ranks as the second leading cause of death. While considerable efforts have been directed at the identification of those who are at risk, most studies have focused on psychosocial and epidemiological factors. This research has identified several variables related to suicide. However, the relatively weak relationships of individual factors to suicidal behavior typically limits their clinical utility. Recent biochemical studies of suicidal behavior in adults have shown that suicide victims and suicide attempters tend to have alterations in serotonergic function. These findings may hold promise for increased prediction of suicide and ultimately, prevention of the act. However, there are no studies to date of biochemical abnormalities in the adolescent suicide population. The purpose of this project is to conduct a large scale multi- measure post mortem study of youth suicide. We will examine the interrelationship among a series of measures of serotonergic function which have been implicated in suicide. It will also examine the correlation between CSF measures of serotonergic function and the measures taken in the brain of the same individual. Extensive diagnostic and background information will be collected for suicide victims and controls in order to correlated biochemical findings with psychiatric information. The major questions to be examined are: 1) Do adolescents who have committed suicide differ from those who have died by other means in measures of serotonergic function; 2) What are the interrelationships among CSF and brain measures of serotonergic function; 3) What is the relationship between diagnosis and other psychiatric information to neurochemical findings in adolescent suicide victims. The results of this project will provide information on the relationships among neurochemical and psychiatric factors in adolescent suicide. These findings may have clinical implications for the identification and treatment of adolescents who are at risk of committing suicide. In addition, this project will help to further elucidate differences and similarities between adolescent and adult suicide e.g. is biochemistry a more important factor in adult than adolescent suicide?