Alterations in resting-state ALFF and functional connectivity linked to implicit and explicit suicidal ideations in...

Area of Science:

• Neuroscience
• Psychiatry
• Brain Imaging

Background:

• Suicidal ideation (SI) is a critical symptom in major depressive disorder (MDD).
• Understanding the neurobiological basis of both implicit and explicit SI is crucial for developing targeted interventions.
• Previous research has not fully elucidated the distinct neural mechanisms underlying different forms of SI.

Purpose of the Study:

• To explore the neurobiological differences between implicit and explicit suicidal ideation (SI) in patients with major depressive disorder (MDD).
• To identify specific brain regions and functional connectivity patterns associated with implicit and explicit SI.
• To investigate the relationship between implicit and explicit SI measures in an MDD cohort.

Main Methods:

• Seventy-four MDD patients and 74 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI).
• Implicit SI was assessed using the Death/Suicide implicit association test (D/S-IAT), and explicit SI using the Beck Scale for Suicidal Ideation (BSSI).
• Amplitude of low-frequency fluctuations (ALFF) and seed-based functional connectivity (FC) were analyzed to map neural activity and networks.

Main Results:

• MDD patients exhibited higher implicit SI, which correlated significantly with explicit SI scores.
• Abnormal ALFF was found in the right postcentral gyrus for implicit SI and in the left insula, postcentral gyrus, and right middle temporal gyrus (MTG) for explicit SI.
• Distinct FC patterns were observed: increased connectivity for implicit SI involving the right postcentral gyrus, and for explicit SI involving the left insula and right MTG.

Conclusions:

• Implicit and explicit suicidal ideation in MDD are associated with partly overlapping yet largely distinct neural substrates.
• Specific alterations in spontaneous brain activity (ALFF) and functional connectivity (FC) differentiate implicit and explicit SI.
• These findings provide novel insights into the neurobiology of SI, potentially informing future therapeutic strategies for depression.