The study will investigate whether a nociceptin receptor antagonist will normalize neural and behavioral processes of approach/avoidance decision-making in unmedicated individuals with major depressive disorder (MDD) and anxiety disorders. More specifically, the study aims to investigate dysregulation within (1) corticostriatal-midbrain circuitry and (2) nociceptin/orphanin FQ peptide and the nociceptin receptor (NOPR).

Inclusion criteria for MDD/anxiety disorder group:

• DSM-5 diagnostic criteria for MDD, Generalized Anxiety Disorder, Social Phobia, Panic Disorder, Post Traumatic Stress (diagnosed using the SCID-5)
• Written informed consent
• For MDD subjects, a baseline Hamilton Depression Rating Scale score > 16 (17-item version)
• Right-handed
• Has a smartphone (iPhone or Android) (needed for Ecological Momentary Assessment)
• Absence of any psychotropic medications for at least 2 weeks (6 weeks for fluoxetine, 6 months for neuroleptics, 2 weeks for benzodiazepines, 2 weeks for any other antidepressants)

Inclusion criteria for healthy controls:

• Absence of medical, neurological, and psychiatric illness (including alcohol and substance abuse), as assessed by subject history and a structured clinical interview (diagnosed using the SCID-5)
• Written informed consent
• Right-handed
• Absence of any medications for at least 3 weeks
• Has a smartphone (iPhone or Android) (needed for Ecological Momentary Assessment)

Exclusion criteria for all participants:

• Subjects with suicidal ideation where outpatient treatment is determined unsafe by the study clinician
• Pregnant women or women of childbearing potential who are not using a medically accepted means of contraception
• Serious or unstable medical illness, including cardiovascular, hepatic, renal, respiratory, endocrine, neurologic or hematologic disease
• History of seizure disorder
• History or current diagnosis of any of the following DSM-IV psychiatric illnesses: organic mental disorder, schizophrenia, schizoaffective disorder, delusional disorder, psychotic disorders not otherwise specified, bipolar disorder, obsessive-compulsive disorder, patients with mood congruent or mood incongruent psychotic features, substance dependence, substance abuse within the last 12 months (with the exception of cocaine or stimulant abuse; which will lead to exclusion)
• History of cocaine or stimulant use (e.g., amphetamine, cocaine, methamphetamine)
• History of use of dopaminergic drugs (including methylphenidate)
• History or current diagnosis of dementia
• Patients with mood congruent or mood incongruent psychotic features
• Current use of other psychotropic drugs
• Clinical or laboratory evidence of hypothyroidism
• Patients with a lifetime history of electroconvulsive therapy
• Failure to meet standard magnetic resonance imaging safety requirements
• Abnormal ECG and lab results
• History of seizure disorder or currently on anticonvulsants

Through the Conte Center website, we will share de-identified data and tools with the scientific community (e.g., code developed by the Computational Modeling Core). In close collaboration with NIMH, we will develop a certification similar to the "NIMH Data Archive Data Use Certification" currently used by NIMH.

Through the National Database for Clinical Trials Related to Mental Illness, we will share five principal human datasets generated within the Conte Center: (1) Clinical rating scales and self-report scales of affect, mood, symptoms and functioning; (2) Behavioral performance during approach-avoidance tasks; (3) Electrophysiological data; (4) Functional magnetic resonance imaging data; and (5) Hormonal (cortisol) responses.

Through ClinicalTrials.gov, we will share the primary and secondary outcomes.