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 and young adults aged 10-24, male and female of all races and ethnicity.
• Participants must be English-speaking (because several study assessments are only available in the English language), however the parent(s) or legal guardian may either speak English or Spanish as the consenting process can be conducted bilingually.
• Adults age 18 and older must be able to provide written informed consent; for youth younger than age 18, a parent or legal guardian must provide written informed consent, and the child or teen must provide written informed assent.
• Ability to complete clinical evaluations and neuropsychological testing.
• Individuals who are unable to provide informed consent.
• Participants who are non-English speaking.
• Individuals with any of the following psychotic features: MDD with psychotic features, schizophrenia, schizoaffective disorder, or other Axis I psychotic disorder.
• Individuals with a depression diagnosis or a history of depression diagnosis at the initial visit (participants who develop depression during the longitudinal follow-up will continue in the study).
• A PHQ-9 score of 10 or greater.
• Individuals who are unable to provide a permanent home address and contact information.
• Individuals with any condition for which, in the opinion of the investigator, study participation would not be in their best interest (e.g., compromise their well-being) or that could prevent, limit, or confound the protocol-specified assessments.

1. Be 8 to 20 years of age; 2. Have a positive screen for depression (e.g., based on PHQ-2 (score ≥3) and/or PHQ-A of 10 or greater, OR positive for suicidal ideation or behavior (e.g., based on CHRT-SR or PHQ-A item 9); OR be in treatment for depression; 3. Be willing to provide consent/assent (parents/LAR/guardian or young adult participant, aged 18-20, must be willing to provide consent; youth, aged 8-17, must be willing to provide assent); 4. Be able to speak English or Spanish sufficiently to understand the study procedures and provide written informed consent to participate in the study; 5. Be willing to dedicate appropriate time to complete scheduled study assessments and measures (both parent/LAR/guardian and youth). 6. Be able to provide a reliable means of contact. 1. Have an acute medical or psychological condition(s) that that would, in the judgment of the study medical clinician, make participation difficult or unsafe; 2. Have an acute medical or psychological condition(s) that would result in an inability to accurately complete study requirements (e.g., neurological conditions or significant neurodevelopmental concerns); 3. Have active psychotic symptoms resulting in altered mental status and inability to provide assent or requiring immediate attention and/or higher level of intervention; 4. Have a parent/LAR/guardian who is deemed cognitively unable to provide consent (if youth participant, aged 8-17).

• Both obese and non-obese (normal weight) early pregnant women aged ≥18 years old will be permitted to participate in this project.
• No restriction with respect to race and socioeconomic status
• Women with a prior history of complicated pregnancy (i.e., gestational hypertension, preeclampsia, HELLP syndrome, gestational diabetes, preterm birth, intrauterine growth restriction, etc.) will be allowed to participate.
• Obese women with previously diagnosed OSA will be allowed to participate if they are not currently on any recognized treatments such as Continuous Positive Airway Pressure (CPAP), oral appliances or nasal expiratory positive airway pressure.
• Those who have had surgery for OSA in the past will be excluded.
• Women taking low-dose aspirin will be allowed to participate in this project.
• Current multiple pregnancy;
• Known major fetal chromosomal or anatomical abnormalities;
• Recurrent miscarriage (three or more);
• Chronic essential hypertension (systolic BP >140 mmHg and/or diastolic BP >90 mmHg);
• Any evidence of cardiovascular and pulmonary diseases by history or by physical examination;
• Kidney disease (serum creatinine >1.5 mg/dL);
• Coagulation disorders;
• Diabetes mellitus (fasting glucose ≥126 mg/dL or 2-hour oral glucose tolerance test glucose level ≥200 mg/dL) or other systemic illness;
• Any evidence of neurological disease;
• Psychiatric disease or psychological disorders;
• History of drug or alcohol abuse within the last 2 years; and
• Given the effects of exercise training on sympathetic neural control, endurance-trained athletes will be excluded. As this project focuses on sleep apnea in pregnancy, Women with other significant sleep disorders such as restless legs syndrome by Rest Leg Syndrome Diagnostic Index and insomnia by the Insomnia Severity Index or Pittsburgh Sleep Quality Index will be excluded; In addition, women who report taking a sleeping aid >1 time per month will be excluded.

• 18-65 years of age (SZ); 18-75 years of age (CON)
• Women and men
• All races and ethnicities
• Psychiatric diagnoses: Patient participants (SZ): Meet DSM-5 criteria for schizophrenia or schizoaffective disorder Healthy control participants (CON): No personal history of lifetime psychiatric disorders, or a family history of psychotic disorders in 1st-or 2nd- degree relatives
• Able to read, speak, and understand English
• Able and willing to provide written informed consent; and willing to commit to the study protocol, including 2-year longitudinal follow-up • Compromised cognitive function: Both SZ and CON participants: Estimated premorbid intellectual ability <75 age-corrected score on Wide Range Achievement Test-4/Word Reading Subtest (WRAT-4) CON participants: <26 score on the Montreal Cognitive Assessment (MoCA)
• Neurological or medical disorder that may affect brain function (history of stroke, head injury with a loss of consciousness >10 min, seizure disorder, AIDS, poorly controlled hypertension, poorly controlled diabetes, decompensated lung disease, etc.)
• Co-morbid DSM-5 diagnosis of drug/alcohol use disorder in prior 3 months
• Current treatment with benzodiazepine or non-benzodiazepine sedatives/hypnotics, and/or anticonvulsants
• Presence of ferromagnetic objects in body
• Weight or body size exceeding MRI scanner capacity [>300 lbs]
• Claustrophobia in MRI scanner
• Pregnant women
• Breastfeeding women (VASO scan will not be administered. All other imaging modalities are safe to administer.)
• Impaired kidney function: Glomerular Filtration Rate (GFR) < 30 ml/min/1.73m2 (VASO scan will not be administered due to an association between Gadolinium-based MR contrast use and Nephrogenic Systemic Fibrosis in individuals with severely impaired renal function. All other imaging modalities are safe to administer.)
• History of hypersensitivity to any MRI contrast agent (VASO scan will not be administered. All other imaging modalities are safe to administer.)