This study will examine the long-term effects of lithium used to treat children and adolescents with aggressive conduct disorder (severe aggression).

Psychotherapeutic agents are often administered without sufficient testing to children and adolescents, often on a long-term basis, to reduce aggression. Many pressures, including managed care, will increase the utilization of pharmacotherapy in the outpatient setting to treat serious problems. Lithium is the most promising agent for the treatment of aggression in children and adolescents. However, it has not been shown that lithium is an effective treatment for these patients in the outpatient (non-hospital) setting, or on a long-term basis. The purpose of this study is to examine the long-term effects of lithium used to treat children and adolescents with aggressive conduct disorder (severe aggression).

The proposed study is a two-phased clinical trial of lithium for the treatment of aggression in conduct disorder. Both phases are double-blind and placebo-controlled with randomization and employ a parallel groups design. Phase 1 contains a short-term 8-week controlled trial, with twice as many subjects randomized to lithium as placebo, increasing the pool of potential lithium responders to continue to Phase 2. In Phase 2, lithium responders from Phase 1 enter a 6-month long-term controlled trial. Every attempt is made to define responders to lithium.

Inclusion Criteria:

1. Males and females
2. Ages between 9 and 17 years.
3. Conduct disorder according to DSM-IV (As rated on the DICA-IV).
4. The aggression criterion at screening

Exclusion Criteria:

1. Mental Retardation.
2. Pervasive Developmental Disorder(s).
3. Major Depressive Disorder or Dysthymic Disorder.
4. Bipolar Disorder.
5. Psychotic Disorder (including Schizophreniform Disorder and Schizophrenia).
6. Major medical problem such as cardiac, renal, and thyroid diseases, or seizure disorder.
7. History of psychoactive medication in the previous 2 weeks.
8. Current Pregnancy in females.
9. History of Substance Dependence in the past month.
10. Prior to the proposed study, a history of lithium treatment with serum lithium levels of 0.4 mEq/L or higher for a cumulative period of greater than 10 days.