Diminished Frontal Pole Size, Functional Connectivity Linked to Elevated Suicide Risk in Young Adults
- This study examined functional MRI data and information about suicidal thoughts and behaviors in a cohort of medication-free college students
- Young adults with elevated levels of suicidality exhibited a smaller right frontal pole, and reduced functional connectivity of the right frontal pole with the bilateral inferior frontal cortex, compared with young adults with the lowest suicidality score
- In young women, suicidality scores were significantly negatively correlated with right frontal pole size
- If these findings are confirmed, brain imaging data could become a component of quantitative algorithms intended to predict which young adults are at high risk of suicidal behavior
Structural neuroimaging research has demonstrated reduced size of the prefrontal cortex in people with a history of suicidal behavior and attempts. However, these studies typically include patients who are being treated for serious psychiatric conditions, often with multiple medications, which may confound the results.
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Massachusetts General Hospital researchers have found similar results, among suicidal young adults who have received no psychiatric treatment. Their findings, published in the Journal of Affective Disorders, may permit earlier identification of individuals at risk.
Gwang-Won Kim, PhD, a research fellow, Maurizio Fava, MD, psychiatrist-in-chief at the Department of Psychiatry, Daphne J. Holt, MD, PhD, director of the Resilience and Prevention Program and co-director of the Psychosis Clinical and Research Program in the Department of Psychiatry, and colleagues authored the study.
The researchers recruited 102 young adults (73% female, mean age 19.5), drawn from a survey-based study of psychopathology, who had no history of neurological or psychiatric disorders. All participants completed three brief questionnaires:
- Suicidal Behaviors Questionnaire-Revised (SBQ-R); total possible score 3–18
- Beck Depression Inventory (BDI)
- Peter's Delusion Inventory (PDI)
High suicidality (HS) was defined as an SBQ-R score ≥8 (n=20) and low suicidality (LS) was SBQ-R of 3 (n=37).
The participants also underwent one session of neuroimaging in a 3Tesla MRI scanner. The analyses focused on eight regions of interest (ROI) within the medial prefrontal cortex: the right and left superior frontal cortex, frontal pole, anterior cingulate cortex, and medial orbitofrontal cortex.
The researchers calculated correlations between SBQ-R scores and the surface areas of the eight ROIs:
- Scores in the full sample were not significantly correlated with surface areas of the ROIs
- For women and not men, right frontal pole surface area was negatively correlated with SBQ-R score (r = −0.34; p=0.004)
Previous research has indicated decreased frontal pole size may be associated with impairments in higher-order cognitive functions, such as decision-making, response inhibition, imagining future events and emotional regulation, all of which are risk factors for suicidal behavior.
When the HS and LS groups were compared directly, the surface area of the right frontal pole, and no other ROI, was significantly lower in the HS group, even after adjustment for BDI score.
Functional Connectivity Analysis
The researchers also explored whether the functional connectivity of the right frontal pole, in addition to its size, was linked to suicidality:
- SBQ-R score was not correlated with functional connectivity between the right frontal pole and other brain regions, either in the full sample or when women and men were analyzed separately
- However, compared with the LS group, the HS group exhibited significantly lower connectivity between the right frontal pole and three areas of the inferior frontal cortex (IFC), a key hub in the circuits that mediate cognitive control
The latter result has not been reported previously. Reduced connectivity between the right frontal pole and IFC might be associated with impaired executive function, decision-making and memory, which may lead to higher levels of suicidality in people with greater levels of negative affect.
The Potential for Early Intervention
Neuroscientists are keenly pursuing investigations of changes in brain structure or function that could reliably predict suicidal behavior. If these findings are confirmed, neuroimaging assessments of the frontal pole could become a component of quantitative algorithms intended to predict which young adults are at high risk of suicidal behavior.
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