Despite increasing suicide rates in adolescents, there remains a paucity of approaches to use to prevent re-attempts. Any hope for breaking the code to prevent youth suicide lies in understanding biological factors that play a role. Evidence suggests that inflammation and immune system dysfunction may be linked to suicide. The investigators will develop immune profiles for adolescents with suicidal behavior and those at risk in order to develop tools that can be implemented for prevention efforts.

This study involves blood draws, answering questions, and completing questionnaires - no treatment or intervention is provided as part of this study. Participants will be screened to see if they qualify for this study using questionnaires.

Participants will be teens (ages 12-18 years) with recent suicidal behavior, teens at-risk for developing depression, and healthy control teens. Participants complete all study-related tasks four times over a period of 12 months. Electronic surveys will be sent to participants to complete monthly. Both the adolescent and if applicable, their parent (or legally authorized representatives, LARs), will answer questions regarding depression, anxiety, and suicidal thoughts/behaviors.

The purpose of this study is to map inflammatory dysfunction to suicidal behavior and establish a reliable immune signature of suicide risk that can 1) guide future research into fundamental pathophysiology and 2) identify targets for drug development and guide clinical screening and risk management.

Background: In previous research, the investigators have identified targets of clinical utility for both suicide-risk identification and novel therapeutic development. Specifically, a state of immune hyper-reactivity that predisposes to suicidal behavior can be corrected by use of immunomodulatory agents.

Blood tests screening for presence of autoantibodies may be implemented as diagnostic tests to predict future suicide risk. Monoclonal antibodies have gained recent attention for their use in CNS disorders (such as multiple sclerosis and migraine) and have been shown to be effective for some patients with depression.

However, the utility of anti-inflammatory treatments for depression has been limited by a lack of biomarkers to guide their use. Thus, presence of autoantibodies may identify a sub-group of adolescents and young adults with suicidality who are candidates for treatment with monoclonal antibodies.

The investigators specifically hypothesize that depressed youths with suicide behavior have immune hyper-reactivity, as reflected in dysfunctional cells mediating both innate and adaptive immune response.

Study Items: Since this is an observational study, investigators will explore a comprehensive panel of carefully selected participant specific parameters: socio-demographic (age, ethnicity, economic); symptom severity measures (depressive symptoms, mood, and feelings); clinical (medical history, anxious depression, early life trauma), biological (biomarkers in blood), behavioral (cognitive, emotional), with the goal to develop the most robust predictive models of treatment response and of depression outcomes. There is no medication or non-medication treatment or intervention provided by this study.

Inclusion Criteria

Study participants must:

1. Be adolescents (aged 12-18 years);

2. Have the ability to speak, read, and understand English. The parent(s) or legal guardians of minors must also speak, read and understand English;

3. Be willing to provide consent/assent. Consent will be provided by parents/LAR/guardian for youth under age 18 or by young adult participant, aged 18. Youth, aged 8-17, must be willing to provide assent;

4. Have the ability to complete clinical evaluations and self-report measures;

5. Meet criteria for one of these three groups:

   1. Adolescent with suicidal behaviors, defined as having a recent (within 3 months) suicide attempt or suicidal ideation warranting urgent evaluation;
   2. Adolescents at risk for mood disorders, defined by either personal history of anxiety disorder or substance use disorder or a history of trauma, or a first degree relative with a history of a mood disorder or suicidal history;
   3. Healthy adolescents with no lifetime history of any psychiatric or substance use disorders or a history of trauma. Additionally, no first-degree family member with a history of a mood disorder or suicidal history..

Exclusion Criteria

Study participants must not:

1. Have current poorly controlled asthma, acute/chronic infection or other medical condition(s) that may affect immune marker levels;
2. Have a current medication (e.g., corticosteroids) that may affect immune marker levels of reactivity;
3. Have any condition for which, in the opinion of the investigator or designee, study participation would not be in their best interest (including but not limited to cognitive impairment, unstable general medical condition, intoxication, active psychosis) or that could prevent, limit, or confound the protocol-specified assessments;
4. Be unable to provide a stable home address and contact information

Adolescents with suicidal behavior, at risk for mood disorder, and/or healthy controls will be recruited from several sources. Some examples include existing pathways (i.e., patient population, participants of ongoing/previous longitudinal studies) as well as an open invitation to the public for enrollment.