Development of a three-factor neuropsychological approach for detecting minimal hepatic encephalopathy

Background: Minimal hepatic encephalopathy (HE) has profoundly negative effects on daily functioning ad quality of life. However, standard psychometric procedures have not been widely incorporated into efforts to develop a neuropsychological battery for this condition. Aims: To establish the construct and diagnostic validity of a neuropsychological approach for the recognition of minimal HE in patients with cirrhosis. Methods: A comprehensive battery of neuropsychological tests was administered to cirrhotic patients with at most grade 1 HE, recruited from the liver transplant and advanced liver disease clinics. An inflammatory bowel disease comparison group was similarly evaluated, thus controlling for the secondary effects of chronic illness on cognition. Testing results for the cirrhosis group were subjected to principal component analysis to establish the relevant cognitive constructs and associated measures. Factor analysis was applied to the neuropsychological battery of 20 tests to determine the cognitive factors to be used. Age-adjusted standardized neuropsychological factor scores were then compared for the two groups. Results: Factor analysis revealed that our battery of 20 tests was measuring three cognitive factors. Based on the pattern of factor loadings, we labeled these important cognitive factors: global cognitive function; psychomotor speed; and learning and memory. Logistic regression revealed that only impaired psychomotor speed distinguished cirrhotics with no more than grade 1 HE from medically ill controls. Conclusions: The cirrhosis group was characterized by a pattern of preserved global cognitive functioning, mild memory impairment, and moderate psychomotor speed impairment. Discussion: This distinctive pattern of focal psychomotor speed deficits is suggestive of subcortical pathway involvement in minimal HE.