Suicidal thoughts and behaviors (STB) increase drastically during adolescence, and presently, suicide is the second leading cause of death among 10-24-year-olds. However, the brain mechanisms underlying adolescent STB remain unclear, and it is difficult to predict which adolescents who ideate about suicide will engage in suicidal behaviors.
Studying brain and psychosocial factors can indicate who is at increased risk for STB whereas acute stress experience, particularly social rejection, often precede suicide attempts and thus may indicate when risk is highest. Critically, we aim to test a diathesis-stress model of STB. Notably, neither factor alone is likely sufficient, and thus, predisposing risk and stressors must be considered together to clarify STB risk.
We will enroll depressed and ideating adolescents—with (N=30) or without (N=30) a recent suicide attempt—from our pediatric emergency department, who are at high risk for suicidal behaviors within our 3-month follow-up. At baseline, we will examine a novel, non-invasive MRI method for quantifying neuromelanin as a proxy for midbrain dopaminergic function. Task-based fMRI will probe adolescent processing of peer acceptance and rejection as well as inhibitory control. Finally, stress is complicated and difficult to assess accurately, and consequently, we will use two complementary approaches to balance their strengths and weakness: stress interviews at baseline and 3-months will provide in-depth but retrospective report while daily smartphone surveys will provide brief but in-the-moment assessment.
Comparing ideating adolescents with and without a prior attempt, we hypothesize that adolescents with a prior attempt will exhibit midbrain dopaminergic deficits. This is the first test of this in vivo in an adolescent STB population. Next, we predict that prior attempters will exhibit greater neural sensitivity to peer rejection, reduced neural sensitivity to acceptance, and reduced neural signatures of inhibitory control. Last, we predict that these neural risk factors will heighten the impact of ongoing social stress on longitudinal STB (including plans, preparatory behaviors, attempts, psychiatric hospitalizations).
Overall, these data will greatly advance our understanding of adolescent STB risk. This project would build on a small body of extant research examining neural mechanisms, which has rarely probed factors differentiating ideators and attempters or examined longitudinal risk–two critical questions for the field. As the sample size is relatively limited, these data will provide initial insights into the diathesis-stress model as well as yielding critical preliminary findings for future NIMH and AFSP grants. This will be an immense benefit and launch pad in my progression as an early stage investigator in the field of adolescent suicide. Furthermore, we hope to combine elements of this data with ongoing projects in the lab to increase the sample size and utility of these data, e.g. comparing to non-ideating but depressed adolescents. Ultimately, I will utilize the data from this project to advance our theories of suicide and to build new projects examining related mechanisms in younger at-risk populations that better predict longitudinal suicide risk.