Functional Imaging of the Implicit Association of the Self With Life and Death

Abstract

Objective: A critical need exists to identify objective markers of suicide ideation. One potential suicide risk marker is the Suicide Implicit Association Task (S-IAT), a behavioral task that uses differential reaction times to compare the implicit association between the self and death to the implicit association between the self and life. Individuals with a stronger association between the self and death on the S-IAT are more likely to attempt suicide in the future. To better understand the neural underpinnings of the implicit association between self and either life or death, a functional magnetic resonance imaging (fMRI) version of the S-IAT was adapted and piloted in healthy volunteers.

Method: An fMRI version of the S-IAT was administered to 28 healthy volunteers (ages 18-65, 14F/14M).

Results: Behavioral results were comparable to those seen in non-scanner versions of the task. The task was associated with patterns of neural activation in areas relevant to emotional processing, specifically the insula and right ventrolateral prefrontal cortex.

Conclusions: Performance on the S-IAT fMRI task may reflect scores obtained outside of the scanner. In future evaluations, this task could help assess whether individuals at increased risk of suicide display a different pattern of neural activation in response to self/death and self/life stimuli.

Trial registration: ClinicalTrials.gov NCT00088699.

Conflict of interest statement

Conflict of Interest

Dr. Zarate is listed as a co-inventor on a patent for the use of ketamine in major depression and suicidal ideation; as a co-inventor on a patent for the use of (2R,6R)-hydroxynorketamine, (S)-dehydronorketamine, and other stereoisomeric dehydro and hydroxylated metabolites of (R,S)-ketamine metabolites in the treatment of depression and neuropathic pain; and as a co-inventor on a patent application for the use of (2R,6R)-hydroxynorketamine and (2S,6S)-hydroxynorketamine in the treatment of depression, anxiety, anhedonia, suicidal ideation, and post-traumatic stress disorders. He has assigned his patent rights to the U.S. government but will share a percentage of any royalties that may be received by the government. All other authors have no conflict of interest to disclose, financial or otherwise.

© 2019 The American Association of Suicidology.

Figures

Figure 1:

Areas of greater activation during the self-death versus self-life blocks. Crosshairs are centered at the peak activation of the right inferior frontal/insula cluster: [−47 −17 3] (scale: Z-score; left=right). Graph represents extracted values of functional magnetic resonance imaging (fMRI) activation during the self-death and self-life blocks in the right inferior frontal gyrus/insula cluster (error bars = +/− 1 standard error).