A research group including Professor Jiro Nakayama proposes a novel therapeutic strategy for early-stage hepatic encephalopathy

Rifaximin improves cognitive function in patients with covert hepatic encephalopathy

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Points

• In a multicentre randomized controlled trial, the research group demonstrated that the rifaximin [1] is effective in improving cognitive function in patients with covert hepatic encephalopathy [2].
• Rifaximin was shown to reduce the risk of events associated with the progression of hepatic encephalopathy, such as falls and traffic accidents, and may contribute to improved quality of life and prognosis in patients with liver cirrhosis.
• Because rifaximin selectively acts on specific bacterial taxa while maintaining the overall diversity of the gut microbiota [3], it is expected to serve as a novel therapeutic strategy that does not substantially disrupt the intestinal environment, with potential for early-stage intervention and future clinical application.

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Abstract

A research team including Specially Appointed Assistant Professor Hiroki Inada, Associate Professor Toshinori Toyota, and Professor Yasuhito Tanaka of Kumamoto University, Professor Hisashi Hidaka of Kitasato University, and Professor Jiro Nakayama of the Faculty of Agriculture, Kyushu University conducted a randomized controlled trial in patients with covert hepatic encephalopathy and demonstrated that the gut-selective antibiotic rifaximin improves cognitive function and reduces the incidence of complications associated with hepatic encephalopathy.
In this study, cognitive function was evaluated using the Stroop test [4], and by combining this with analyses of the gut microbiota, the researchers demonstrated the clinical efficacy of rifaximin as well as part of its mechanism of action. These findings highlight the potential of a novel therapeutic strategy targeting covert hepatic encephalopathy, an early stage of the disease before overt symptoms become apparent.
The results of this study were published in the online edition of the journal Alimentary Pharmacology & Therapeutics on May 6, 2026 (Japan time).

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Glossary

1) Rifaximin
An antibiotic that acts within the intestinal tract and is thought to contribute to the improvement of hepatic encephalopathy by modulating the gut microbiota.
2) Covert hepatic encephalopathy
A condition in which there is no overt disturbance of consciousness, but mild impairments in cognitive functions such as attention and judgment are present.
3) Gut microbiota
A diverse community of microorganisms residing in the intestine that plays important roles in digestion, immunity, and neural function.
4) Stroop test
A cognitive test that evaluates attention and processing speed by exploiting the interference between color recognition and word meaning.

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Publication Information

Title: Rifaximin Improves Cognitive Performance and Reduces Cirrhosis-Related Adverse Events in Covert Hepatic Encephalopathy: A Randomized Controlled Trial
Authors: Hiroki Inada, Toshinori Toyota, Haruki Uojima, Etsuko Iio, Takao Miwa, Satoshi Miuma, Shiho Miyase, Takahiro Mizuta, Daiki Maeda, Katsuya Nagaoka, Satoshi Narahara, Sotaro Kurano, Kentaro Tanaka, Yoko Yoshimaru, Takehisa Watanabe, Shuichiro Iwasaki, Hisashi Hidaka, Kazuhiro Sugi, Hiroko Setoyama, Masahito Shimizu, Jiro Nakayama, Yasuhito Tanaka
Journal: Alimentary Pharmacology & Therapeutics
doi：10.1111/apt.70712

• For more details on this research, click here.

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For Research-related inquiries

Jiro Nakayama, Professor