Thalamus Changes May Drive Brain Network Damage in Liver Cirrhosis Before Overt Symptoms

Liver cirrhosis has long been known to reach beyond the liver, quietly reshaping the brain even in patients who show no obvious signs of cognitive trouble. A new neuroimaging study now offers one of the most detailed pictures yet of how this happens, revealing that the thalamus, a deep-brain relay station, may be the driving force behind widespread structural changes across the cerebral cortex in patients with cirrhosis who have not yet developed overt hepatic encephalopathy. The findings, published in BMC Medical Imaging, combine advanced network analysis of brain structure with gene-expression mapping to trace how liver dysfunction progressively rewires the brain.

The research, led by Lubin Gou and Junqiang Lei of the First Hospital of Lanzhou University and Lanzhou University’s First Clinical Medical College, focused on patients with liver cirrhosis without overt hepatic encephalopathy, a stage abbreviated LC-nOHE. This is the window in which the disease has already compromised liver function but has not yet produced the confusion, disorientation, and personality changes that define overt hepatic encephalopathy. Understanding what happens in the brain during this silent phase is critical, because it may reveal the earliest opportunities for intervention before irreversible damage takes hold.

The team recruited 86 patients with liver cirrhosis but no overt encephalopathy, along with 62 healthy controls, and acquired high-resolution three-dimensional T1-weighted magnetic resonance images of every participant’s brain. From these scans, the researchers extracted the volume of the thalamus and three distinct measures of cortical shape: cortical thickness, sulcal depth, and fractal dimension, a measure of the complexity of the brain’s folded surface. Rather than examining these features in isolation, the investigators constructed structural covariance networks, mathematical maps in which brain regions are connected if their anatomical features covary across individuals. Such networks are widely used as proxies for coordinated maturational and degenerative processes, offering a window into how brain regions change together as a system.

The results were striking at multiple levels. Compared with healthy controls, patients with cirrhosis showed enlargement of the thalamus alongside a broad range of cortical morphological abnormalities. At the level of whole-network organization, the thalamo-cortical structural covariance networks of patients displayed reduced segregation, meaning the brain’s specialized modules were less clearly differentiated, and decreased integration, meaning efficient communication across the network was impaired. These two properties, segregation and integration, are hallmarks of a healthy, well-organized brain, and their simultaneous deterioration suggests a fundamental disruption of the architecture that supports cognition.

Zooming in on individual network nodes, the researchers found that the centrality of three regions was significantly reduced in patients: the thalamus itself, the supramarginal gyrus, and the insula. Each of these regions plays a recognizable role in the syndrome. The thalamus relays sensory and motor signals to the cortex and regulates consciousness and alertness; the supramarginal gyrus contributes to language and spatial cognition; and the insula supports interoception and awareness of the body’s internal state. Reduced centrality in these hubs indicates that they had lost influence within the network, becoming less connected to the rest of the brain’s structural architecture.

Perhaps the most clinically significant finding was the relationship between brain changes and liver function. The degree centrality of the thalamus was negatively correlated with liver function measures, meaning that the worse the liver was performing, the more the thalamus had lost its position within the brain’s structural network. This correlation ties the brain imaging directly to the severity of liver disease and supports the idea that the thalamus sits at the front line of the liver-brain axis, the pathway by which hepatic dysfunction, circulating toxins such as ammonia, and systemic inflammation are translated into neural injury.

To move beyond correlation and probe causality, the team applied a technique called causal analysis of structural covariance networks, or CaSCN. This approach examines how changes in one brain region’s morphology relate to changes in others across the progression of disease, allowing researchers to ask which region leads and which follows. The analyses demonstrated that thalamus volume had causal effects on the alterations of cortical morphology as liver dysfunction progressed. In other words, the data are consistent with a model in which the thalamus is not merely another victim of cirrhosis but an active driver, propagating structural changes outward to the cortical regions with which it is connected.

The study then took an unusual additional step: linking the brain imaging to genomics through imaging transcriptomics. Using normative gene-expression profiles from the Allen Human Brain Atlas, the researchers evaluated whether the spatial pattern of causal effects across the cortex overlapped with the spatial distribution of specific genes. It did. The pattern of causal path coefficients was spatially correlated with the expression of particular genes in the normative atlas, suggesting that the cortical regions most vulnerable to thalamus-driven change are also those with distinctive molecular signatures. Gene ontology analyses pointed toward enrichment in biological processes, molecular functions, and cellular components that may help explain why some cortical areas are preferentially affected while others are relatively spared.

Taken together, the findings provide a comprehensive, multilevel view of how the thalamo-cortical circuit becomes progressively vulnerable in liver cirrhosis before overt encephalopathy appears. The enlargement of the thalamus, consistent with processes such as edema or glial changes reported in prior literature on hepatic encephalopathy, appears to initiate a cascade that erodes the segregation and integration of the entire structural network, strips key hubs of their centrality, and reshapes the cortex in patterns governed partly by underlying gene expression. Because the thalamus’s network position tracks liver function, measures of thalamo-cortical network integrity could potentially serve as imaging biomarkers for identifying patients at risk of progressing to overt hepatic encephalopathy, enabling earlier monitoring and treatment.

The authors emphasize that these findings offer a potential mechanism-driven framework for understanding the earliest brain consequences of liver disease, one that connects organ function, network neuroscience, and transcriptomics within a single analytical pipeline. The work was supported by the Lanzhou University First Affiliated Hospital Foundation and the Science and Technology Department of Gansu Province, and it was approved by the Institutional Ethics Committee of the First Hospital of Lanzhou University. As cirrhosis continues to affect millions worldwide, studies like this one bring clinicians closer to detecting, and perhaps preventing, the neurological toll of liver disease before it announces itself in the clinic.

Subject of Research: Structural covariance network alterations of the thalamo-cortical circuit in liver cirrhosis patients without overt hepatic encephalopathy

Article Title: Multilevel structural covariance network alterations of thalamo-cortical circuit in liver cirrhosis patients without overt hepatic encephalopathy: associations with liver function and imaging transcriptomics

Article References: Gou, L., Ren, H., Xu, W., Gao, Y., Wang, S., Zhang, Y., Dou, Y., & Lei, J. (2026). Multilevel structural covariance network alterations of thalamo-cortical circuit in liver cirrhosis patients without overt hepatic encephalopathy: associations with liver function and imaging transcriptomics. BMC Medical Imaging. https://doi.org/10.1186/s12880-026-02790-6

Image Credits: AI Generated

DOI: 10.1186/s12880-026-02790-6

Keywords: liver cirrhosis, hepatic encephalopathy, thalamus, thalamo-cortical circuit, structural covariance network, MRI, liver-brain axis, imaging transcriptomics, cortical thickness, liver function, neuroimaging, Allen Human Brain Atlas