How do I administer the Trail Making Test (TMT) in an office for an adult being screened for dementia, including required equipment, instructions, scoring, and considerations for vision, motor function, and language comprehension?

Trail Making Test Administration in Office Settings

The Trail Making Test (TMT) is a quick, public-domain cognitive screening tool that requires only paper, pencil, and a stopwatch, making it ideal for office-based dementia screening, though it cannot distinguish between different types of dementia. 1

Required Equipment

• Stopwatch or countdown timer 1
• TMT Part A and Part B test sheets (freely available, public domain) 1
• Pencil without eraser 1
• Clipboard or flat writing surface 1
• Quiet, well-lit room with minimal distractions 1

Pre-Test Considerations

Essential Screening Before Administration

Before starting, verify the patient has adequate vision to see the numbers/letters on the page, sufficient motor function to hold a pencil and draw lines, and can comprehend the task instructions in their primary language. 1

• Check visual acuity—patient must be able to clearly see 1-2 cm sized numbers and letters on the page 1
• Assess motor function—patient must have sufficient hand control to draw connecting lines (tremor or mild arthritis is acceptable) 1
• Confirm language comprehension—patient must understand instructions about connecting numbers in sequence or alternating between numbers and letters 1
• Note any factors that may affect performance: educational level, age, and any history of conditions affecting cognition (stroke, alcohol use) 1

Administration Protocol

Part A: Numbers Only

Part A measures psychomotor speed and visual attention by having patients connect 25 consecutive numbers (1-2-3-4, etc.) as quickly as possible. 1

1. Place the Part A test sheet on a flat surface in front of the patient 1
2. Give clear instructions: "Draw a line connecting the numbers in order, starting at 1 and going to 2, then 3, and so on, as quickly as you can. Do not lift your pencil from the paper." 1
3. Demonstrate by pointing (not drawing) from 1 to 2 to 3 1
4. Start timing when the patient touches pencil to number 1 1
5. If the patient makes an error, immediately point it out and have them return to the last correct circle before continuing (do not stop timing) 1
6. Stop timing when the pencil touches circle 25 1
7. Record total time in seconds 1

Part B: Alternating Numbers and Letters

Part B assesses set-shifting, divided attention, and cognitive flexibility by requiring patients to alternate between numbers and letters (1-A-2-B-3-C, etc.). 1, 2

1. Place the Part B test sheet in front of the patient 1
2. Give instructions: "This time, connect the circles by alternating between numbers and letters. Start at 1, then go to A, then 2, then B, and so on. Work as quickly as you can." 1
3. Demonstrate by pointing from 1 to A to 2 to B 1
4. Follow the same timing and error correction procedures as Part A 1
5. Record total time in seconds 1

Scoring and Interpretation

Primary Outcome Measures

The main score is total time to completion in seconds for each part, with scores >2 standard deviations above age-adjusted norms indicating impairment. 1, 2

• Part A primarily reflects psychomotor speed and visual scanning 1
• Part B reflects executive function, particularly set-shifting and divided attention 1, 2
• The difference score (Part B minus Part A) isolates executive function from basic processing speed 1
• Number of errors should also be recorded, though time is the primary metric 1

Age and Education Adjustments

Scores must be interpreted using age-adjusted and education-adjusted normative data, as both factors significantly affect performance. 1

• Older adults take longer to complete both parts 1
• Higher education levels correlate with faster completion times 1
• Published normative tables are available for different age and education groups 1
• Consider scores between 1-2 SD as mild deficit, >2 SD as definite impairment 1, 2

Critical Limitations and Pitfalls

Diagnostic Specificity

The TMT is highly sensitive to cognitive impairment but cannot distinguish vascular cognitive impairment from Alzheimer's disease or other conditions—it requires combination with imaging and risk factor assessment for differential diagnosis. 1

• Abnormal scores occur in multiple conditions: stroke, traumatic brain injury, Parkinson's disease, coronary artery bypass, and various dementias 1
• The test should never be used alone for diagnosis 1
• Combine with domain-specific tests (memory, language, visuospatial) for comprehensive assessment 1, 2

Test Characteristics Affecting Difficulty

Part B is harder than Part A not only due to cognitive demands but also because it is physically longer (56 cm more line drawing) and has more visual distractions on the page. 3

• The increased motor demands and visual clutter contribute to longer completion times independent of executive function 3
• This means Part B time reflects a mixture of motor speed, visual search, and executive abilities 3, 4

Practice Effects

Repeat testing within 12 months shows significant practice effects, so use the same version and compare to healthy controls tested at similar intervals, or wait >12 months between administrations. 1, 2

• Learning effects occur with repeated administration 1, 2
• Few well-standardized alternate forms exist 1
• Serial testing is valuable for detecting progressive decline but requires controlling for practice effects 1, 2

Integration with Comprehensive Assessment

For dementia screening, combine the TMT with tests of episodic memory (word-list learning with delayed recall), language (naming, fluency), and a global screening tool (MoCA or MMSE). 1, 2

• The TMT alone does not assess memory, the most common early deficit in Alzheimer's disease 1, 5
• Add tests like Hopkins Verbal Learning Test or logical memory subtests to evaluate episodic memory 1, 5
• Include language assessment (Boston Naming Test, category fluency) and visuospatial testing (figure copying) for comprehensive evaluation 1
• Consider adding Digit Symbol Substitution Test, which is also highly sensitive to cognitive impairment and complements the TMT 1