*6.3.1.1 Number connection tests*

The NCT-A accesses the visual-spatial orientation and psychomotor speed. Twenty-five circles numbered from 1 to 25 are scattered randomly on a sheet of paper. The patients must connect the numbers in order in the shortest time possible without mistakes. If a mistake is made, the subject must stop, correct the error, and then continue without stopping the clock. The test score is the time needed to perform the test, including the time needed to correct all errors. Poorer performance is shown by a longer time for completion (**Figure 3**). In the NCT-B **(Figure 4**), the numbers from 1 to 13 and the letters from A to L were included in circles. The patient is asked to connect numbers and letters in alternating manner, that means go from 1-A-2-B-3-C and so on. Test outcome is the time needed by the patient to perform the test, including error correction time. Besides visuospatial orientation and psychomotor speed, this test is suitable to study the ability to shift attention [78].

According to the guidelines of the International Society for Hepatic Encephalopathy and Nitrogen Metabolism [79], the results of NCT-A will be considered abnormal when the test scores are more than the mean + 2 standard deviations (SDs) from the age-matched normal values. A newly developed electronic number connection test (eNCT) was developed*.* This test flashes the numbers 1–25 on a screen and needs the participant to click them in order while being timed [80]. These tests are time-consuming, and their results are influenced by age and educational status. However, these tests are recommended for diagnosis of MHE [42, 81].

**Figure 3.** *Number connection tests-A.*

#### **Figure 4.** *Number connection tests-B.*

#### **Figure 5.** *Digit symbol test.*
