Funding has been terminated for this study.

Depression and bipolar disorder are major public health concerns for adolescents today. Teenage depression and bipolar disorder are associated with social isolation, family stress, school failure, substance abuse and suicide. Screening for depression and bipolar disorder so that treatment can be started early in the course of illness is an urgent public health priority. Many teens with bipolar disorder are incorrectly diagnosed as having unipolar depression. It is critical that adolescents receive proper screening and assessment that leads to an accurate diagnosis and treatment. An efficient, cost-effective, blood-based screening program could be performed on an annual or semi-annual basis to potentially detect depression and then differentiate between unipolar and bipolar depression. If this type of screening were able to detect a significant percentage of teens with depression or bipolar disorder, the positive impact on U.S. public health would be substantial. The purpose of this study is to conduct a pilot study to assess the probability of detecting adolescent unipolar and bipolar depression through blood samples.

Inclusion of Major Depressive Disorder Participants:

1. Male and female patients between the ages of 13 and 17 years
2. Participants must be able to give informed assent, and parent(s)/guardian(s) must be able to give informed permission for study participation
3. Diagnosis of MDD or depression not otherwise specified, as defined by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-TR criteria (DSM-IV-TR)
4. Current mood state depressed for > 2 weeks

Inclusion of Bipolar Disorder Participants:

1. Male and female patients between the ages of 13 and 17 years
2. Participants must be able to give informed assent, and parent (s)/guardian (s) must be able to give informed permission for study participation
3. Diagnosis of Bipolar I Disorder, Bipolar II Disorder, or not otherwise specified, as defined by Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition-TR criteria
4. Current mood state depressed for > 2 weeks

Inclusion of Healthy Control Participants:

1. Males and females between the ages of 13 and 17 years
2. Participants must not meet DSM-IV-TR diagnostic criteria for a psychiatric or substance abuse disorder
3. Participants must be able to give informed assent and parent (s)/guardian (s) must be able to give informed permission for study participation

Exclusion Criteria:

Exclusion of Major Depressive Disorder and Bipolar Disorder Participants:

1. Meet the DSM-IV criteria for substance abuse or dependence in the last month
2. History of fainting or other significant adverse event during blood draws in the past
3. Dysthymia
4. Daily use of oral or inhaled steroids
5. High risk of suicidal behaviors, homicidal behaviors, or self-harm
6. A medical condition, such as Addison's Disease, which is highly likely to influence the inflammatory or HPA responses

Exclusion of Healthy Control Participants:

1. Clinically significant psychiatric or substance abuse disorder
2. Unstable medical or neurological illness
3. History of fainting or other significant adverse event during blood draws in the past
4. Daily use of oral or inhaled steroids
5. A medical condition, such as Addison's Disease, which is highly likely to influence the inflammatory or HPA responses

Participants who respond to recruitment flyers displayed within the community.