Test-retest reliability of data for all tests was assessed using the ICC (model 2), which is appropriate for methodological research. Reliability of data obtained for the TUG and gait speed was assessed using the ICC (2,2), as mean scores from 2trials from each test session were used in the calculations. Mean scores are considered better estimates of true scores and can increase reliability estimates.13 For calculation of test-retest reliability for the 6MWT, the ICC (2,1) was used, as there was only one test score from each ses- sion. For each clinical test, the reliability coefficient was calculated for the entire sample and then separately for the mild to moderate AD group and the moderately severe to severe AD group.