Learning and Memory Impairments in Patients with Minimal Hepatic Encephalopathy are Associated with Structural and...

Area of Science:

• Neuroscience
• Hepatology
• Cognitive Science

Background:

• Minimal hepatic encephalopathy (MHE) is characterized by subtle cognitive deficits, particularly in attention and executive functions.
• Existing research has not fully explored the connection between memory impairments in MHE and the structural and functional integrity of the hippocampal system.
• The hippocampus plays a crucial role in learning and memory, making it a key area to investigate in MHE.

Purpose of the Study:

• To investigate verbal learning and long-term memory performance in cirrhotic patients with (C-MHE) and without (C-NMHE) MHE, as well as in healthy controls.
• To examine the relationship between memory deficits and alterations in the structural integrity and functional connectivity (FC) of the hippocampal system in these groups.
• To identify specific hippocampal subfields and networks associated with memory impairments in MHE.

Main Methods:

• Cross-sectional study comparing three groups: cirrhotic patients with MHE (C-MHE), cirrhotic patients without MHE (C-NMHE), and healthy controls.
• Assessment of verbal learning, long-term memory, and recognition using standardized neuropsychological tests.
• Structural MRI to measure hippocampal subfield volumes and fimbria volume.
• Functional MRI (fMRI) to analyze resting-state functional connectivity (FC) within the hippocampal system, focusing on seed regions like the presubiculum and subiculum.

Main Results:

• C-MHE patients demonstrated significant impairments in learning, long-term memory, and recognition compared to both C-NMHE patients and healthy controls.
• Cirrhotic patients (both C-MHE and C-NMHE) exhibited reduced fimbria volume compared to controls.
• Larger hippocampal subfield volumes correlated with better memory performance in C-NMHE patients and controls, but not in C-MHE patients.
• C-MHE patients showed reduced FC between the left presubiculum and left precuneus compared to C-NMHE patients.
• Compared to controls, C-MHE patients displayed reduced FC between the left presubiculum/subiculum seeds and the bilateral precuneus, with these reductions correlating with cognitive impairment and memory performance.

Conclusions:

• Learning and long-term memory impairments in cirrhotic patients with MHE are associated with structural disturbances and altered functional connectivity within the hippocampal system.
• Reduced functional connectivity in hippocampal networks, particularly involving the presubiculum and precuneus, may underlie the cognitive deficits observed in C-MHE.
• These findings highlight the importance of the hippocampal system's structural integrity and functional network dynamics in maintaining memory function in the context of liver cirrhosis and MHE.