Trail Making Test: What It Measures and How It Works

Why the Trail Making Test Matters

If a neurologist, memory clinic, or neuropsychologist has mentioned a timed "trails" task, this is almost certainly it. The Trail Making Test has been in use for decades and remains one of the most widely administered neuropsychological measures in the world, in part because it is quick, needs only pencil and paper, and can be given in about 5 to 10 minutes (Bowie & Harvey, 2006).

It matters to families because the test does something clever with very little: by comparing how a person performs on a simple sequencing task versus a more demanding one, it gives a clinician a window into the parts of thinking that often shift early. Understanding what it does — and does not — measure helps you make sense of a result and ask better questions. If you are new to the broader topic, our overview of cognitive testing explains where brief tasks like this fit alongside other tools.

What the Trail Making Test Measures

Rather than testing one ability in depth, the Trail Making Test briefly samples a cluster of related skills. A recent review describes the split clearly: Part A evaluates visuoperceptual tracking and processing speed, while Part B adds divided attention, set-shifting, and cognitive flexibility (Tsiakiri et al., 2024).

In everyday language, that means:

• Visual scanning — the eyes' ability to search a page and find the next target quickly.
• Processing speed — how fast a person can take in information and act on it.
• Attention — staying focused and not losing the thread mid-task.
• Set-shifting and mental flexibility — switching back and forth between two rules, which is the extra demand Part B introduces.

These last skills fall under what clinicians call executive function — the brain's "management" system for planning, switching, and staying on track. Because Part B leans on executive function so heavily, the difference between the two parts is often more informative than either part alone.

How the Test Works (Part A and Part B)

The format is simple to picture. In Part A, a person draws a line connecting a series of numbered circles in ascending order, as quickly and accurately as they can. In Part B, the circles contain both numbers and letters, and the person alternates between the two sequences — number, letter, number, letter — again working against the clock (Bowie & Harvey, 2006).

That alternating rule in Part B is the whole point: it forces the brain to hold two sequences in mind and flip between them, which is far more demanding than counting up in a single line. A clinician times each part and notes any errors, gently redirecting the person if they lose their place so the task keeps moving.

Because it is a proprietary, professionally administered instrument, the actual test forms are used and scored by trained clinicians rather than practiced at home — repeatedly rehearsing a screening task can distort what it is designed to reveal. It is one of many types of cognitive tests a clinician may draw on.

How Scores Are Interpreted

The Trail Making Test is scored primarily by time — how many seconds it takes to complete each part accurately — rather than by a tally of right answers. Longer completion times, especially a large gap between Part A and Part B, can point toward slowed processing or reduced mental flexibility.

Crucially, there is no universal "pass" number. Performance changes naturally with age and education: a large normative study of community-dwelling adults found that times increased with older age and fewer years of schooling, which is why clinicians compare a result against norms matched to a person's age and education rather than a single cutoff (Tombaugh, 2004). A time that is perfectly typical for one person could be unusual for another. This is exactly why results are clinician-interpreted; for more on reading any score in context, see how to understand cognitive test results.

When It's Used

Clinicians reach for the Trail Making Test in a range of situations — as part of a broader cognitive workup, when screening for changes in attention or executive function, or when tracking recovery after an event such as a stroke or head injury. Its brevity makes it easy to include alongside other measures without adding much time to a visit.

It rarely travels alone. More often it is one component of a larger battery, and when a deeper picture is needed it appears within a full neuropsychological evaluation that combines many tasks. Another familiar pencil-and-paper task a clinician may pair it with is the clock drawing test, which samples a different but overlapping set of skills.

What Happens Next

A slower-than-expected time on the Trail Making Test is a prompt, not a verdict. On its own, it cannot diagnose dementia, Alzheimer's disease, or any other condition. As the Alzheimer's Association explains, there is no single test that determines whether someone is living with Alzheimer's or another dementia — clinicians combine cognitive assessments with medical history, physical and neurological exams, and sometimes brain imaging or lab work (Alzheimer's Association).

When a result raises questions, a clinician may look for treatable contributors — such as thyroid problems, vitamin deficiencies, poor sleep, stress, or medication side effects — before drawing any conclusions. The aim at every step is clarity and next steps, not alarm.

Taking the Next Step

To see how this task compares with other tools a clinician might use, start with our guide to the different types of cognitive tests.

If you'd like a structured, repeatable way to check in on memory and thinking from home between clinician visits, explore how Orena's FDA-cleared at-home test works.