The clock-drawing test is a brief cognitive screen with meaningful but imperfect accuracy; it cannot diagnose dementia by itself. Cost depends on the setting, and an abnormal result should lead to a fuller medical assessment rather than a diagnosis based on the drawing alone. The test can help identify people who may need further evaluation. It is less dependable for mild cognitive impairment, and a normal result does not settle every concern.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- What the test can and cannot tell you
- How accurate is the clock-drawing test?
- Is it useful for mild cognitive impairment?
- What should happen after a concerning result?
- What does testing cost?
What the test can and cannot tell you
The clock-drawing test checks cognitive performance through a short task. Clinicians may use the result as one piece of an initial assessment. An abnormal score suggests that further investigation may be worthwhile.
It does not establish whether the cause is dementia, another health problem, or a temporary change. The U.S. Preventive Services Task Force describes brief cognitive tests as screening tools, not stand-alone diagnostic tests. Medical, neuropsychological, laboratory, or imaging evaluation may be appropriate after an abnormal result.
How accurate is the clock-drawing test?
Accuracy depends partly on how the drawing is scored. Different scoring systems emphasize different errors and use different thresholds for an abnormal result. A 2018 meta-analysis covering 18 studies and 5,531 participants reported these results for detecting dementia: Sensitivity measures how often a test identifies people who have dementia.
Specificity measures how often it correctly clears people who do not. The meta-analysis indexed by PubMed therefore shows a tradeoff: Shulman scoring detected more cases, while Sunderland scoring produced fewer positive results among people without dementia. These figures are study estimates, not a person's probability of having dementia. Even with Shulman scoring, some participants with dementia screened negative, while some without dementia screened positive.
- Shulman scoring: 82.0% sensitivity and 75.7% specificity.
- Sunderland scoring: 72.6% sensitivity and 87.9% specificity.
Is it useful for mild cognitive impairment?
The evidence is weaker for mild cognitive impairment, often called MCI. MCI describes cognitive difficulty that may be subtler than dementia, making it harder for a brief clock task to detect reliably. A systematic review found that reported sensitivity and specificity for MCI were mostly unsatisfactory.
It concluded that the clock-drawing test should not be used to screen for MCI. Routine screening also requires context. For adults aged 65 and older who live in the community and have no symptoms, the USPSTF found insufficient evidence to determine whether routine cognitive screening produces more benefit than harm. That finding is neither a recommendation for nor against screening.
What should happen after a concerning result?
Do not treat one abnormal drawing as proof of dementia. Cognitive changes can have several possible causes, including medication effects, metabolic or endocrine problems, illness-related delirium, depression, and different dementias.
A comprehensive assessment may examine: The National Institute on Aging advises clinicians to investigate an abnormal screen because the screening result alone cannot identify the cause or diagnose dementia. If symptoms continue despite a normal clock test, describe those changes to a clinician rather than relying on the score.
- Changes noticed by the person and someone who knows them well.
- Ability to manage everyday activities.
- Prescription and nonprescription medicines.
- Mood, behavior, and safety concerns.
- Whether specialist evaluation or a care plan is needed.
What does testing cost?
For Medicare patients, cost depends on how the assessment is provided. A cognitive assessment included in an eligible yearly Wellness visit costs nothing when the provider accepts assignment, according to Medicare's Wellness visit coverage information.
A separate comprehensive cognitive assessment generally leaves the patient responsible for 20% of the Medicare-approved amount after the Part B deductible. Before the appointment, ask whether the visit qualifies as a Wellness visit, whether the provider accepts assignment, and whether a separate assessment will be billed.
