Cognitive Function Assessment Using the Stroop Test: Exploring the Broader Therapeutic Potential of L-Ornithine L-Aspartate (LOLA, Hepa-Merz), a Hepatic Encephalopathy Medication

Abstract

Background: L-Ornithine L-Aspartate (LOLA), known commercially as Hepa-Merz, is widely used in the treatment of hepatic encephalopathy (HE) due to its ability to facilitate ammonia clearance via both urea and glutamine pathways. In addition to its established role in HE, emerging evidence suggests LOLA may aid liver regeneration, support mitochondrial function, and reduce oxidative stress. This study investigates LOLA's potential impact on cognitive performance in individuals with minimal hepatic encephalopathy (MHE), utilizing the Stroop Test as a neuropsychological evaluation tool and correlating findings with serum ammonia concentrations.

Methods: Sixty-five patients diagnosed with MHE underwent cognitive evaluation before and after administration of LOLA. Ammonia levels were quantified both pre- and post-intervention. The Stroop Test, including Stroop Word (SW), Stroop Color (SC), Stroop Color-Word (SCW), and the Total Stroop Test (TST), was used to assess changes in cognitive speed and accuracy. Data were analyzed using unpaired t-tests to evaluate the significance of observed changes.

Results: Post-treatment results showed a significant decrease in blood ammonia levels (from 123.2 ± 27.1 µmol/L to 112.7 ± 24.1 µmol/L, p < 0.05). All Stroop Test components demonstrated marked improvement, with faster TST indicating better cognitive processing. Moreover, patients with initially elevated ammonia levels tended to perform worse on cognitive testing, reinforcing the link between hyperammonemia and cognitive dysfunction.

Conclusion: Hepa-Merz demonstrates efficacy in reducing systemic ammonia and enhancing cognitive function in MHE patients. The Stroop Test proves to be a sensitive and practical measure for detecting neurocognitive changes and treatment effects. These findings support further exploration of LOLA’s (Hepa-Merz) benefits beyond traditional HE management, particularly in preserving or improving brain function.