Clinical utility of the Trail Making Test practice time.

The Trail Making Test (TMT) is one of the most frequently used measures in clinical neuropsychology. Data obtained from the TMT practice times were analyzed to determine their utility in predicting success and failure on the full version of the test and to allow establishment of criteria by which to judge administration or discontinuation of the full test. Results indicated that TMT practice times were useful in predicting successful completion of Part A and B of the TMT. Tables are provided which describe the classification accuracy of various TMT practice times. These tables allow clinicians to select a practice-time cutoff and then use the cutoff as a heuristic to assist in the decision to administer the remainder of that particular part of the TMT or discontinue the test. A 20-s cutoff resulted in optimal prediction of successful completion (< 180 s) of TMT Part A. A cutoff of 30 s optimally predicted successful completion (< 300 s) of TMT Part B.