Smaller cornu ammonis (CA3) as a potential risk factor for suicidal behavior in mood disorders

Area of Science:

• Neuroscience
• Psychiatry
• Genetics

Background:

• Mood disorders and suicidal behavior exhibit moderate heritability and familial transmission.
• Smaller hippocampal volumes are associated with these conditions, but the cause (heritable risk, epigenetic factors, or illness effects) remains unclear.

Purpose of the Study:

• To differentiate hippocampal substructure volume alterations related to familial risk versus illness or treatment effects.
• To identify potential biological risk markers for mood disorders and suicidal behavior in individuals with high familial risk.

Main Methods:

• Structural brain imaging and hippocampal substructure segmentation (Cornu Ammonis CA1-4, dentate gyrus, subiculum) were performed.
• High-risk (HR) individuals with a family history of mood disorder and suicide attempt were compared to healthy volunteers (HV).
• Independent cohorts were used to validate findings in individuals with and without mood disorder and suicidal behavior.

Main Results:

• Unaffected high-risk individuals (HR) showed lower CA3 (Cornu Ammonis 3) hippocampal volume compared to healthy volunteers (HV).
• This finding aligns with previous studies in individuals with mood disorder and suicidal behavior (MOOD+SA), suggesting a familial risk marker.
• Reduced CA3 volume may mediate familial suicide risk and serve as a risk indicator.

Conclusions:

• Smaller CA3 hippocampal volume appears to be a heritable risk marker for mood disorders and suicidal behavior.
• This hippocampal substructure may be a therapeutic target for suicide prevention strategies in high-risk families.