Functional brain network changes associated with clinical and biochemical measures of the severity of hepatic encephalopathy

Tun Jao, Manuel Schröter, Chao Long Chen, Yu Fan Cheng, Chun Yi Zac Lo, Kun Hsien Chou, Ameera X. Patel, Wei Che Lin*, Ching Po Lin, Edward T. Bullmore

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

28 Scopus citations

Abstract

Functional properties of the brain may be associated with changes in complex brain networks. However, little is known about how properties of large-scale functional brain networks may be altered stepwise in patients with disturbance of consciousness, e.g., an encephalopathy. We used resting-state fMRI data on patients suffering from various degrees of hepatic encephalopathy (HE) to explore how topological and spatial network properties of functional brain networks changed at different cognitive and consciousness states. Severity of HE was measured clinically and by neuropsychological tests. Fifty-eight non-alcoholic liver cirrhosis patients and 62 normal controls were studied. Patients were subdivided into liver cirrhosis with no outstanding HE (NoHE, n= 23), minimal HE with cognitive impairment only detectable by neuropsychological tests (MHE, n= 28), and clinically overt HE (OHE, n= 7). From the earliest stage, the NoHE, functional brain networks were progressively more random, less clustered, and less modular. Since the intermediate stage (MHE), increased ammonia level was accompanied by concomitant exponential decay of mean connectivity strength, especially in the primary cortical areas and midline brain structures. Finally, at the OHE stage, there were radical reorganization of the topological centrality-i.e., the relative importance-of the hubs and reorientation of functional connections between nodes. In summary, this study illustrated progressively greater abnormalities in functional brain network organization in patients with clinical and biochemical evidence of more severe hepatic encephalopathy. The early-than-expected brain network dysfunction in cirrhotic patients suggests that brain functional connectivity and network analysis may provide useful and complementary biomarkers for more aggressive and earlier intervention of hepatic encephalopathy. Moreover, the stepwise deterioration of functional brain networks in HE patients may suggest that hierarchical network properties are necessary for normal brain function.

Original languageEnglish
Pages (from-to)332-344
Number of pages13
JournalNeuroImage
Volume122
DOIs
StatePublished - 15 11 2015
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2015.

Keywords

  • Brain networks
  • Consciousness
  • Hepatic encephalopathy
  • Liver cirrhosis
  • Resting-state fMRI

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