The interrelationship of hepatic encephalopathy and motor functioning in cirrhosis

Abstract

Cirrhosis is a late stage of liver disease characterized by scarring of the liver. It is one of the leading causes of mortality worldwide, with cognitive impairment and physical frailty among the most debilitating symptoms. Cognitive dysfunction occurs due to hepatic encephalopathy, a neurotoxic complication of liver disease. These symptoms are often subtle and go undetected. Complications of hepatic encephalopathy and motor weakness are associated with increased hospitalizations and mortality in this population. The relationship between domains of cognitive functioning and motor performance has a strong base in the aging literature and several disease populations, however, this association has not been well demonstrated in cirrhosis. Thus, the current study examined the impact of cognitive functioning on motor performance in cirrhosis in order to target these modifiable risk factors and improve patient health. Disease severity was then analyzed as a moderator between cognitive and motor performance. Finally, we explored the impact of dual-task performance on gait speed and cognitive accuracy, and the moderating effects of disease severity and neuropsychological performance on this relationship. A sample of 38 participants were prospectively enrolled from an ambulatory transplant clinic and completed a battery of physical tasks (i.e., Short Physical Performance Battery (SPPB), Liver Frailty Index (LFI)), neuropsychological tests (i.e., Test of Premorbid Functioning, Golden Stroop, Controlled Oral Word Association Test, Animal fluency, Repeatable Battery for the Assessment of Neurological Status Figure Copy and Recall, Hopkins Verbal Learning Test – Revised, and Psychometric Hepatic Encephalopathy Score), and a dual-task paradigm with three experimental conditions: Single Task Walking (STW), Single Task Counting backward by 3’s (STC), and Dual Task Walking (DTW). Gait velocity was measured using a 40-foot walkway and cognitive accuracy was defined as the rate of numbers subtracted correctly per minute. Results indicated that attention/processing speed was associated with total SPPB performance, gait speed, and handgrip strength. Executive functioning was related to gait speed, handgrip strength and total LFI score. Visuospatial processing was associated with total LFI score. When the attentional system was taxed with the additional demands of DTW, gait speed was reduced. Cognitive accuracy was quantitatively lower but did not reach statistical significance. There was an interaction effect between dual-task performance and cognitive capacity, but not disease severity. In sum, results support the limited existing literature on the relationship between cognitive and motor functioning in cirrhosis. To our knowledge, this is the first study to examine dual task performance in this population. Understanding this relationship can lead to earlier detection of compromised cognitive and motor functioning, and introduction of novel interventions to prevent cirrhosis-related complications.