Lower resting state functional connectivity between the hippocampus and default network is associated with suicidal...

Area of Science:

• Neuroscience
• Psychiatry
• Neuroimaging

Background:

• Suicidal ideation (SI) is a critical risk factor for suicidal behavior.
• Understanding the neural underpinnings of SI is crucial for developing assessment tools.
• Previous research linked SI to altered hippocampal activity (Amplitude of Low Frequency Fluctuations - ALFF).

Purpose of the Study:

• To investigate the role of hippocampal functional connectivity (FC) in adults with major depressive episodes and SI.
• To compare resting-state FC patterns between individuals with and without SI.

Main Methods:

• Used functional magnetic resonance imaging (fMRI) to assess resting-state FC in unmedicated adults with major depressive episodes.
• Employed a previously identified hippocampal region of interest (ROI) with higher ALFF in SI individuals as a seed for whole-brain FC analysis.
• Validated findings in a larger, independent dataset (REST-MDD).

Main Results:

• Hippocampal FC to the Default Network (DN) was significantly lower in participants with SI compared to those without SI.
• This reduced connectivity was observed in both the primary cohort and the validation dataset, indicating cross-dataset convergence.
• Intra-network FC within the DN regions was not significantly associated with SI, highlighting a specific hippocampal-DN connection.

Conclusions:

• Resting-state hippocampal functional connectivity is associated with the presence of suicidal ideation in major depressive disorder.
• Reduced coupling between the hippocampus and the Default Network may represent a neural correlate of SI.
• Longitudinal studies are warranted to explore how changes in clinical status impact this FC pattern.