Last updated on March 2020

Neurobiology of Suicide

Brief description of study


There are no good treatments for people considering suicide. Researchers want to study suicide with questions, blood tests, brain imaging, and sleep studies. They hope to better understand suicide, so they can help suicidal people.


To understand what happens in the brain when someone has thought about or attempted suicide.


Group 1: Adults ages 18 70 who have thought about or attempted suicide recently

Group 2: Adults ages 18 70 who have thought about or attempted suicide in the past

Group 3: Adults ages 18 70 who have depression or anxiety, but have never thought about suicide

Group 4: Healthy volunteers the same ages.


Participants will be screened in another protocol. Adults who have recently thought about or attempted suicide must be referred by a doctor. They may do up to 3 phases of this study. Groups 2, 3 and 4 will do only Phase 1 and will not get ketamine.

Phase 1: 1 week in hospital. Participants will have:

Physical exam.

Questions about thoughts and feelings.

Thinking and memory tests and simple tasks.

Blood and urine tests.

Two MRI scans. Participants will lie on a table that slides into a metal cylinder that takes pictures. They will have a coil over their head and earplugs and do a computer task.

Sleep test. Disks and bands will be placed on the body to monitor it during sleep.

Magnetic detectors on their head while they perform tasks.

A wrist monitor for activity and sleep.

Lumbar puncture (optional). A needle will collect fluid from the back.

Shock experiments (optional). Participants will observe pictures and sounds and feel a small shock on the hand.

Phase 2: 4 days in hospital. A thin plastic tube will be placed in each arm, one for blood draws, the other to get the drug ketamine once. Participants will repeat most of the Phase 1 tests.

Phase 3: up to 4 more ketamine doses over 2 weeks.

Participants will have follow-up calls or visits at 6 months and then maybe yearly for 5 years.

Detailed Study Description

  1. Objective

Suicide occurs across demographics and psychiatric disorders, killing at least one million individuals worldwide each year. In contrast to other injury-related death such as homicide or motor vehicle accidents, suicide rates have increased, particularly among middle-aged adults. Clinicians have a limited ability to predict imminent suicidal behavior and few, if any, efficacious treatments are available to treat suicidal patients. Advances in the treatment of the suicidal patients have been hampered by an incomplete understanding of the neurobiological underpinnings of the suicidal crisis, as suicidal thoughts and behaviors have not been clearly linked with specific neural circuits.

The aim of this study is to evaluate possible biomarkers of suicidal thoughts and behaviors in individuals currently experiencing a suicidal crisis. In taking a dimensional approach to suicide research, we will be able to study phenomenology across Research Domain Criteria (RDoC) units of analysis, from genes through circuits to self-report and experimental paradigms. Through this approach, we can identify potential neurobiological risk factors for both short and long-term suicide risk. As a secondary aim, we will use ketamine to identify biomarkers of ketamine response in a sample at acute risk for suicide.

B. Study Population

Five participant populations will be recruited into this protocol in order to encompass the continuum of suicide risk. A total of 325 individuals will be enrolled in the study. Participant populations are individuals with the following conditions: 1.) recent suicidal ideation with intent and/or suicide attempt (Group 1- active crisis , n= 65); 2) a past history of suicide attempt, but no suicidal behavior in the last year (Group 2, n= 65, attempters ); 3) anxiety or mood symptoms, but no recent or past suicidal thoughts or behavior (Group 3, n= 65);

4) healthy controls with no psychiatric or suicide history (Group 4, n= 65); and lifetime suicidal thoughts with intent (Group 5, n=65, ideators ).

C. Design

The research protocol will occur across three phases: baseline, ketamine response and optional repeated infusions. All participants will first be consented into Phase I, which may last up to seven days. This baseline phase will entail multimodal assessment, using pathophysiological markers (blood draw, lumbar puncture), neuroimaging (fMRI, MEG), polysomnography, clinical ratings and experimental paradigms (shock experiments). Participants will receive their regularly scheduled daily medications, but will not receive additional treatment (including new prn medications, such as benzodiazepines for management of anxiety or agitation) during this brief baseline phase. After completion of Phase I, eligible participants from Group 1 only (active crisis) will be offered participation in Phase II, the ketamine response phase. This phase, which will last up to four days, consists of a single, open-label trial of ketamine (0.5 mg/kg). The focus of this phase will be identification of potential biomarkers of antisuicidal ketamine response. Participants who complete Phase II will be offered Phase III, which will involve repeated ketamine infusions over two weeks (2 times/ per week for 2 weeks). Psychiatric medication adjustment will be permitted during Phase III.

After participation in Phases I-III, participants in Groups 1-3 and 5 will be offered standard clinical treatment (excluding healthy controls), or participation in another protocol. In standard clinical treatment, adjustment of psychiatric medications and commencement of psychotherapeutic interventions will be permitted. Finally, participants in the first three groups (excluding healthy controls) will receive follow-up evaluations at six months and 1 year after completion of Study Phase I.

D. Outcome Measures

In Phase I, the outcome measures will be underlying psychiatric, psychological, neuroimaging, sleep and biological differences between the participant groups. In Phase II, the outcome measures will be reductions in suicidal thoughts and depressive and anxiety symptoms at 24 hours post-ketamine infusion.

Clinical Study Identifier: NCT02543983

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