Discrepancy analysis and Australian norms for the Trail Making Test.

Area of Science:

• Neuropsychology
• Cognitive Psychology
• Clinical Psychology

Background:

• Discrepancy analyses compare two measures within an individual, often using tests like the Trail Making Test (TMT).
• TMT Trails A and B are frequently compared, but analyses often neglect the impact of Trails A performance level.
• Existing methods may not fully account for differential vulnerability to pathology or performance variability.

Purpose of the Study:

• To investigate the utility of TMT discrepancy analysis stratified by Trails A performance levels.
• To differentiate between slowed visual scanning/graphomotor speed and reduced mental flexibility.
• To provide a more nuanced understanding of cognitive performance in clinical cases.

Main Methods:

• Utilized a normative sample of 647 Australians and a clinical sample of 2,292 Australians and U.S. participants.
• Employed discrepancy analysis comparing TMT Trails A and TMT Trails B.
• Stratified analyses based on the performance level of TMT Trails A.

Main Results:

• Demonstrated the ability to differentiate between perceptual-motor speed and mental flexibility deficits by stratifying TMT discrepancies.
• Highlighted the importance of considering Trails A performance variability in discrepancy score interpretation.
• Applied normative data to clinical cases, revealing distinct patterns of impairment.

Conclusions:

• A simple, efficient approach for analyzing TMT-A and TMT-B differences is presented.
• This method allows for examination of the relative contributions of perceptual/motor abilities and mental flexibility.
• Stratifying by Trails A performance enhances the diagnostic utility of TMT discrepancy analysis.