[79] The Critical Flicker Frequency (CFF) test is a psychophysiological tool defined as the frequency

at which a fused light (presented from 60 Hz downward) appears to be flickering to the observer. Studies have shown its reduction with worsening cognition and improvement after therapy. The CFF test requires several trials, intact binocular vision, absence of red-green blindness, and specialized equipment.[80, 81] The Continuous Reaction Time (CRT) test. The CRT test relies on repeated registration of the motor reaction time (pressing a button) to auditory stimuli (through headphones). The most important test result is the CRT index, which measures the stability of the reaction times. The test result can differentiate between organic and ALK inhibitor metabolic brain impairment and is not influenced by the patient’s age or gender, and there is no learning or tiring effect. Simple software and hardware are required.[82] Temsirolimus The Inhibitory Control Test (ICT) is a computerized test of response inhibition and working memory[83]

and is freely downloadable at www.hecme.tv. The ICT test has been judged to have good validity, but requires highly functional patients. The norms for the test have to be elaborated beyond the few centers that have used it. The Stroop test evaluates psychomotor speed and cognitive flexibility by the interference between recognition reaction time to a colored field and a written color name. Recently, mobile application software (“apps” for a smartphone or tablet

computer) based on the test has been shown to identify cognitive dysfunction in cirrhosis compared to paper-pencil tests.[84] Further studies are under way to evaluate its potential for screening for MHE and CHE. The SCAN Test is a computerized test that measures speed and accuracy to perform a digit recognition memory task of increasing complexity. The SCAN Test has been shown to be of prognostic value.[85] Electroencephalography examination can detect changes in cortical cerebral activity across the spectrum of HE without patient cooperation or risk of a learning effect.[70] However, it is nonspecific and may be influenced by accompanying metabolic disturbances, such as hyponatremia as well as drugs. Possibly, the reliability of EEG analysis can increase with quantitative HSP90 analysis. This specifically should include the background frequency with mean dominant frequency or spectral band analysis.[60] Also, in most situations, EEG requires an institutional setup and neurological expertise in evaluation, and the cost varies among hospitals. Although the above-described tests have been used to test for MHE and CHE, there is, most often, a poor correlation between them because HE is a multidimensional dysfunction.[86] Learning effect is often observed with psychometric tests and it is unclear whether current HE therapy plays a role in the test performance.