Trail making test - part B discontinuation is associated with worse performance across multiple cognitive domains,...

Individuals unable to complete neuropsychological tests within designated time limits (i.e. discontinue) are often excluded from statistical analysis. However, discontinuation may represent a meaningful clinical consideration. The present study investigated the clinical utility of discontinuation on the Trail Making Test Part B (TMT-B) as an indicator of cognitive functioning.

The sample included 137 patients (n = 90 completers; n = 47 non-completers) referred for comprehensive outpatient neuropsychological evaluation for primary memory complaints. Mann-Whitney U tests and chi-square tests compared the characteristics of patients who did complete the TMT-B to patients who did not by social demographics, neuropsychological test performance, health literacy/numeracy, and self-report measures of psychological symptoms and functional impairment.

TMT-B discontinuation was associated with significant differences across nearly all cognitive domains (p-adj <.01), including worse performance on measures of language, processing speed, verbal and visual learning and memory, executive functions, nondominant hand fine motor speed/dexterity, and visuoconstruction. Differences between individuals who discontinued TMT-B based on social demographics, psychological symptoms, functional abilities, performance validity measures, dominant hand fine motor speed/dexterity, and basic auditory working memory were nonsignificant.

Discontinuation on TMT-B is associated with significantly worse cognitive performance across nearly all domains of neuropsychological performance. Discontinuation was not associated with any specific clinical diagnosis. Discontinuation could be an indicator of cognitive impairment and may reflect the unique value of the TMT-B as a screening tool for determining appropriate clinical assessment batteries.