The Clock Drawing Test for Dementia

The clock drawing test (CDT) is one of the oldest and simplest cognitive screens. The person is handed a blank sheet (or a pre-drawn circle) and asked to draw a clock, put in all the numbers, and set the hands to a particular time. That is the whole task.

Its usefulness comes from how much it asks the brain to do at once. Drawing a correct clock quietly draws on several abilities together:

• Memory and comprehension — holding the instructions in mind and remembering what a clock looks like.
• Executive function and planning — organising the numbers evenly around the face and placing the hands correctly.
• Visuospatial skill — arranging everything in the right place in space.

Because a problem in any of these areas can distort the drawing, the CDT is used to help flag possible cognitive impairment and to monitor change over time. It is not specific to Alzheimer’s disease — a distorted clock can also appear with other dementias, delirium, or stroke.

In a clinic the administration is brief and standardised. Knowing the steps helps you understand what a result is based on:

1. 1

   Draw the clock face

   The person is asked to draw a round clock. Some versions provide a pre-printed circle so the score focuses on the numbers and hands rather than the circle itself.

2. 2

   Add all the numbers

   They fill in the numbers 1 to 12, in the right places around the face. How evenly and correctly the numbers are spaced is a big part of what the test reveals.

3. 3

   Set the hands to a stated time

   They are asked to draw the hands to show a specific time — commonly "ten past eleven" (11:10), which is chosen because it requires processing both numbers and resists simply pointing the hands at the numbers named.

4. 4

   The clinician reviews the drawing

   The finished clock is scored using one of several systems (below), and — importantly — interpreted in the context of the person’s history, other tests, vision, and education.

A clinician looks less at neatness and more at the *kind* of error. Different mistakes point to different difficulties:

• Numbers crowded together or pushed to one side — often reflects planning and visuospatial difficulty; numbers all on one side can also signal spatial neglect after a stroke.
• Missing, extra, or repeated numbers — repeating numbers or losing track can reflect reduced cognitive flexibility, sometimes seen in Alzheimer’s.
• Hands set to the wrong time, or more than two hands — trouble translating "ten past eleven" into hand positions is a common and telling executive-function error.
• A generally disorganised or incomplete clock — can appear even in earlier stages when planning is affected.

These patterns are clues, not verdicts. A single unusual clock from someone who is tired, anxious, or has poor eyesight is very different from a clearly disorganised clock that fits with other changes a family has noticed.

There is no single official score. Researchers count more than twenty different scoring systems for the clock drawing test, which is one reason it is used alongside other measures rather than alone. Two of the most common:

• The Mini-Cog approach — the clock is scored simply as normal (2 points) or abnormal (0), then added to the three-word recall (0–3) for a total out of 5. On the published Mini-Cog scoring, a total of 0–2 suggests a higher likelihood of clinically important impairment and warrants further evaluation.
• The Shulman method — the clock is rated on a 0–5 scale, with more and more significant errors producing a lower score.

The scoring looks deceptively easy, which is exactly why it is worth being careful. Interpreting a clock properly means weighing the *type* of error against the person’s vision, education, language, mood, and medical history — and comparing it with other tests. A worried family member scoring a clock at the kitchen table can easily read too much into a shaky drawing, or be falsely reassured by a "good enough" one.

This is the part that matters most. A poor clock is a signal, not a sentence. It suggests that something is affecting thinking and is worth investigating — nothing more and nothing less.

Crucially, a distorted clock is not specific to dementia. Several other things commonly affect it, and several are treatable:

• [Delirium](/caregiver-guides/why-is-my-mom-confused-at-night) — a sudden, often reversible confusion from infection, medication, dehydration, or pain, which can wreck a clock temporarily.
• Stroke or other brain injury — which can affect spatial skills specifically.
• Depression — which can slow thinking and mimic cognitive impairment.
• Poor vision, tremor, or arthritis — which affect the drawing itself, not the thinking behind it.
• Limited education, or English as a second language — which can affect performance independent of any impairment.

And a *normal* clock does not rule everything out either — the test is a relatively blunt instrument, and some people with early changes still draw a passable clock. That is exactly why clinicians pair it with other tools and, above all, do not diagnose from it alone.

If a clock — whether drawn in a clinic or informally at home — worries you, the path forward is straightforward:

• See the doctor, and mention when the changes started. A gradual change over months and a sudden change over days point in very different directions — the sudden one is often a treatable problem, not dementia.
• Ask them to rule out reversible causes first — infection, thyroid issues, vitamin deficiency, medication effects, depression, and poor sleep can all affect thinking.
• Expect more than one test. A proper evaluation combines history, a fuller cognitive assessment, a physical exam, and sometimes blood work or imaging — the clock is just one small input.
• Focus on support alongside answers. Whatever the cause, practical help makes daily life safer — a clear dementia clock for day-to-day orientation, a predictable daily routine, and reading up on dementia care at home.

The clock drawing test earns its place because it is quick, cheap, and surprisingly informative. But its value is as a *prompt to look further* — the answer always comes from a full assessment by a professional, never from the drawing alone.