Hippocampal fimbria atrophy and its mediating effect between cerebral small vessel disease and cognitive impairment

Area of Science:

• Neurology
• Neuroimaging
• Cognitive Science

Background:

• Cerebral small vessel disease (CSVD) is a common cerebrovascular condition.
• Cognitive impairment is a frequent complication of CSVD.
• The impact of CSVD on specific hippocampal subregions and its relation to cognitive decline requires further investigation.

Purpose of the Study:

• To investigate the relationship between hippocampal (HP) subregion volume reduction and cognitive impairment in patients with CSVD.
• To identify HP subregions affected by CSVD.
• To explore the role of HP subregion volumes as potential biomarkers for early cognitive impairment detection in CSVD.

Main Methods:

• Cross-sectional study involving 315 participants (146 with CSVD, 169 controls).
• Clinical, cognitive, and magnetic resonance imaging (MRI) data were collected.
• Analysis included comparing HP subregion volumes between groups, regression analysis for risk factors, and mediation analysis for relationships between HP volumes, CSVD burden, and cognitive function.

Main Results:

• Significant volume differences were observed in multiple HP subregions, including CA4 body, presubiculum, subiculum, GC-ML-DG, fimbria, and HP tail, between CSVD and control groups.
• The fimbria was identified as the most significantly impacted HP subregion by CSVD.
• Mediation analysis confirmed that fimbria volume acts as a mediator between total CSVD score and cognitive scores (MoCA/SCWT).

Conclusions:

• Hippocampal subregion volumes, especially the fimbria, are reduced in patients with CSVD.
• Fimbria volume reduction is associated with the severity of CSVD burden and cognitive impairment.
• HP subregion volumes, particularly the fimbria, show potential as early biomarkers for detecting cognitive impairment in CSVD.