Gender and age effects on the continuous reaction times method in volunteers and patients with cirrhosis

Minimal hepatic encephalopathy (MHE) is a metabolic brain disorder occurring in patients with liver cirrhosis. MHE lessens a patient's quality of life, but is treatable when identified. The continuous reaction times (CRT) method is used in screening for MHE. Gender and age effects on the CRT method are unknown and may confound the results. The aim of this study was to standardise the CRT method outcomes for age and gender effects. We studied 121 volunteers without known disease and 181 patients with cirrhosis by a CRT test. Reaction time to an auditory signal was measured 100 times, the 10th, 50th, and 90th reaction time percentiles were recorded, and the CRT index was calculated as the 50th percentile/(90th percentile-10th percentile), as a measure of intra-individual stability in reaction times. In volunteers, men reacted faster than women and their reaction times slowed with age. However, neither the gender nor the age effect was present regarding the CRT index. The patients with cirrhosis reacted slower and with a higher degree of instability than volunteers. Male patients reacted faster than female patients, and reaction times tended to slow with age. As among the volunteers, there was no gender or age effect on CRT index for the patients with cirrhosis. Age and gender influenced reaction times of both volunteers and patients with cirrhosis. The CRT index, however, was independent of age and gender in both groups. Screening of patients with cirrhosis using the CRT index, therefore, identifies brain dysfunction rather than effects of gender and age.