Administration, Scoring, and Interpretation of the Trail Making Test

The Trail Making Test (TMT) is a simple tool that can be used to screen for dementia. It does so with a series of timed tests that can accurately assess a person's cognition (meaning ther ability to think, reason, and remember). Dementia is when the loss of these functions is severe enough to interfere with daily life.

The test is conducted in two parts, each with its specific aims and purposes. The goal of the TMT is to complete the tests as quickly and accurately as possible to reveal any potential signs of cognitive impairment.

This article outlines the history of the Trail Making Test and explains how it is administered and scored. It also looks at how accurate the TMT is in diagnosing cognitive impairment and the benefits and limitations of use.

A doctor talking with his patient in the office
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History of the TMT

The Trail Making Test (TMT) was created in 1944 by Ralph Reiten, an American neuropsychologist who is to be considered to be one of the fathers of clinical neuropsychology.

The test was initially developed for the Army to evaluate the general intelligence of soldiers based on their ability to maintain visual attention and demonstrate "task switching" (the ability to unconsciously shift focus from one task to the next).

In 1946, clinical psychologist Stewart G. Armitage proposed that the test be used to evaluate brain damage sustained by soldiers during the Second World War.

Since then, the TMT has been incorporated into the Halstead-Reitan Neuropsychological Test Battery (HRNB), a comprehensive panel of tests used to assess the condition and functioning of the brain.

How the TMT Is Used Today

The Trail Making Test is commonly used as a tool to identify and diagnose many types of brain impairment, particularly those involving the frontal lobes. This is the part of the brain that controls high-level cognitive skills like planning, self-control, memory formation, empathy, and attention.

An Overview of the Parts of the Test

The TMT can be used in people 15 to 89 who are suspected of having cognitive impairment. It can provide insights into a person's cognitive function based on how fast they can search, scan, and process visual information without losing track of what they are doing.

The test also provides information about a person's mental flexibility (meaning how quickly they can shift from one thought process to another).

All of these abilities are a part of what is known as executive functioning. A marked loss or decline of these abilities may be an indication of cognitive impairment.

The TMT is timed and performed in two parts using only a pen and a piece of paper.

Part A

TMT Part A consists of 25 circles on a piece of paper with the numbers 1 to 25 written randomly in each.

For Part A, the person is tasked with drawing a line from one circle to the next in ascending numerical order, from 1 to 25, as quickly as possible. The lines between the circles are referred to as the "trail."

Part B

TMT Part B consists of 24 circles on a piece of paper, But, rather than all of the circles containing numbers, half contain the numbers 1 to 12 and the other half contain the letters A through L.

For Part B, the person is tasked with connecting the circles in ascending order, alternating back and forth from numbers to letters. In other words, the "trail" would be connected like this:

1-A-2-B-3-C-4-D-5-E-6-F-7-G-8-H-9-I-10-J-11-K-12-L

Test Administration

The TMT is highly sensitive to certain types of cognitive impairment. It does not require specialist training to administer but is conducted in a specific way to ensure accuracy.

The TMT is administered in the following steps:

  1. Give the person the TMT Part A worksheet with the circles and numbers already drawn on them.
  2. Explain the directions, then demonstrate how Part A is done on a sample page.
  3. Start timing the test as soon as the person begins.
  4. If the person makes a mistake, let them know and allow them to correct the mistake and continue.
  5. Record the time when the person is finished.
  6. Repeat with TMT Part B.

If the person is unable to complete Parts A and B after five minutes, you can discontinue the test.

Scoring

The Trail Making Test is scored based on how long it takes to complete the test. There are no penalties for mistakes other than they extend the final recorded time.

The scores are the number of seconds it takes to complete a test. Each part of the test is scored individually. Higher scores indicate a higher degree of cognitive impairment.

Acceptable Scores

Based on the scores, the TMT can provide useful information about two things;

  • Cognitive function is described in relation to the "average" score for each test. Higher scores indicate cognitive decline. Lower scores suggest a person's cognitive abilities are intact.
  • Cognitive impairment is described by scores that exceed a certain time. After that time, a person's score is said to be "deficient."

For TMT Part A and Part B, the "average" and "deficient" scores are categorized as follows:

   Average  Deficient
TMT Part A 29 seconds Over 79 seconds
TMT Part B 75 seconds Over 273 seconds

The values may be adjusted for older adults who often take longer to complete tests even if their cognitive abilities are intact. There is no universal agreement as to what these adjustments should be, but some groups have proposed the following;

   Average  Deficient
TMT Part A (ages 55-75) Up to 42 seconds Over 70 seconds
TMT Part A (ages 75-98) Up to 51 seconds Over 79 seconds
TMT Part B (ages 55-75) Up to 101 seconds Over 273 seconds
TMT Part B (ages 75-98) Up to 128 seconds Over 273 seconds

Effectiveness of Screening

The TMT measures attention, visual screening, memory, and processing speeds. The test has shown good diagnostic accuracy in evaluating a person's cognitive functioning.

TMT Part A is a good measure of working memory.

Part B is generally good at evaluating executive functioning since the test requires multiple abilities. It may also be useful in determining whether someone with dementia can safely drive since the test involves both visual processing and mental flexibility.

With that said, the accuracy of the TMT can vary based on what condition is being investigated. The accuracy is determined by the test's sensitivity (the percentage of times it correctly identifies a person with a disease) and specificity (the percentage of times it correctly identifies a person without a disease).

Variations in TMT Accuracy

Research suggests that the Trail Making Test has a specificity of 86% and a sensitivity of 79% in diagnosing HIV dementia. When used to identify cognitively impaired drivers, the TMT has a sensitivity of only 53% and a specificity of 90%.

The Oral Trail Making Test

The Trail Making Test can also be administered verbally. The oral test can be used when a person is physically unable to perform the written test or in a situation where illness and fatigue might affect the written results.

For Part A, rather than giving the person a piece of paper and pen, you can simply ask the person to count from 1 to 25.

For Part B, the person is asked to verbally recite numbers and letters, alternating between numbers and letters (like 1-A-2-B-3-C, etc.)

Pros and Cons of the Trail Making Test

As beneficial as the test is, there are pros and cons to the Trail Making Test. Depending on the aims of testing, it may not be the right choice for everyone or every situation.

Pros
  • The test is easy and quick to administer.

  • The test does not require specialist training to administer.

  • The test can be performed anywhere.

  • The test offers relatively high accuracy in detecting cognitive impairment.

Cons
  • Older age can skew the results if adjustments are not made.

  • The test accuracy can vary based on the condition being diagnosed.

  • Misdiagnosis is possible in borderline cases if specialist interpretation is not sought.

Summary

A Trail Making Test is a quick and simple test that can help detect cognitive problems like dementia. It is conducted in two parts using only a pen and a piece of paper.

Part A of the test requires you to connect 25 randomly placed circles in ascending numerical order. Part B also requires you to connect 24 randomly placed circles in ascending order, alternating between numbers and letters.

The test is scored based on how many seconds it takes you to complete each part. Higher scores indicate a higher degree of cognitive image. The test, while very useful, may be less accurate in older adults and have varying degrees of accuracy based on the condition being investigated.

A Word From Verywell

As useful as the Trail Making Test is, it is not meant to be used in isolation or to self-test yourself for dementia or any other cognitive problem. The TMT is most beneficial when used as part of a comprehensive panel of screening tests by a qualified healthcare provider.

If you think you or someone you love may have dementia, ask your primary care provider for a referral to a specialist for further evaluation. This may include a neurologist who treats disorders of the brain and nervous system or a geriatrician who specializes in the healthcare of older adults.

Frequently Asked Questions

  • How much time does it take to complete the Trail Making Test?

    The Trail Making Test (TMT) takes less than five minutes to complete. The test is given in two parts, each of which is completed in an average of 29 and 75 minutes respectively. Longer times may be an indication of cognitive impairment.

  • What does the Trail Making Test measure?

    The Trail Making Test measures your visual attention, mental flexibility, processing speed, and motor speed based on how quickly and accurately you connect dots in ascending order (either numerically or with alternating numbers and letters). The test can be used to diagnose dementia and other cognitive disorders.

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7 Sources
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