Your ability to draw a clock may not seem too important, but the clock-drawing test (CDT) in schizophrenia is a clinical tool that can help determine the presence of cognitive decline.

Schizophrenia is a lifelong, progressive mental health condition known for its primary features of psychosis, like hallucinations and delusions. Cognitive decline is also a core part of schizophrenia, however, significantly contributing to why this condition can be impairing.

Research indicates the overall cognitive performance of people with schizophrenia averages two standard deviations below neurotypical controls. It’s a major component of employment challenges and why some people can have a difficult time living independently.

The CDT can’t predict cognitive decline in schizophrenia, but experts can use it as an easy assessment tool to track its current state and progression.

The CDT is not specific to schizophrenia. It’s a decades-old test primarily used to detect dementia, a type of impairing memory loss and cognitive decline seen across many physical and mental health conditions.

The CDT is a simple test that people can score in several ways, with no scoring system considered better than the rest.

A healthcare professional usually asks you to draw a clockface that’s not digital, and they give you specific instructions about how it should look and what time it should indicate.

The healthcare professional assesses the drawing for the number placement accuracy, the position of the clock hands, and the drawing’s overall organization.

What does the clock-drawing test show?

The CDT doesn’t definitively diagnose cognitive decline conditions, but it can point out areas where you’re experiencing cognitive changes.

“The clock-drawing test is a way to test, primarily, a couple of cognitive functions,” explains Dr. Joanna Gan, a board certified neurologist at the Veteran’s Health Administration from Sacramento, California. “Cognitive functions are one’s abilities to learn through our senses, thoughts, and experiences.”

Common deficits the CDT can reveal include:

  • Graphical difficulties: An accurate clock drawing with imprecise lines can indicate a cognitive decline in areas of fine motor control and planning.
  • Stimulus-bound response: Drawing an accurate hour hand with a minute hand positioned to a number rather than the requested time (Eg: Instead of positioning the minute hand at the “2” in the request of “10 after 11,” the person puts the minute hand to the “10.”) can indicate executive function decline.
  • Conceptual deficits: Clock drawings that don’t look like clocks can indicate semantic memory impairment.
  • Special/planning deficits: Errors in the clock drawing’s number layout may suggest impairment in the brain’s right parietal lobe.
  • Preservation: Repetitive drawings, like creating multiple clock hands, also links with executive function decline.
A collection of possible variations on the "clock drawing test" and it's possible interpretations. Share on Pinterest
Different interpretations of the clock-drawing test may indicate different forms of cognitive decline.

In addition to assessing the current cognitive state for a diagnosis, A 2017 study showed that the CDT might be a valuable tool for tracking progress during schizophrenia treatment.

The CDT is not a definitive diagnostic tool for any particular condition. It can help reveal areas of cognitive decline, but cognitive decline can have various underlying causes.

Gan indicates that the CDT is an accurate assessment tool for cognitive decline in schizophrenia.

“Schizophrenia is associated with cognitive dysfunction, particularly executive dysfunction, that is, the ability to plan, perform activities of daily living, such as go shopping, cook, pay bills, etc.,” she says. “It is positively correlated with functional decline and disability in schizophrenia.”

In addition to gauging cognitive decline, research suggests the test may be able to point toward schizophrenia if experts notice certain patterns.

An older, small 2003 study found specific CDT patterns were more common in people with schizophrenia, including difficulty:

  • placing numbers correctly
  • setting the minute hand with the minute number
  • identifying the minute target
  • making the minute hand longer than the hour hand

These patterns were consistent with cognitive decline in the area of the brain known to be affected by schizophrenia, the frontal lobe.

The CDT in schizophrenia isn’t a necessary part of determining a diagnosis. It’s a tool intended to assess cognitive function before, during, or after a person receives a diagnosis.

According to Gan, “failing” the CDT can indicate cognitive impairment, but it often simply means you’ll need further neurological evaluations.

It doesn’t mean you definitively have schizophrenia.

“One can further examine the situation by additional cognitive testing, such as screening measures or a more involved neuropsychology evaluation,” she says. “Screening measures with a good coverage of executive function include the Montreal Cognitive Assessment and the St. Louis University Mental Status Exam.”

She cautions that the CDT may encounter modern-day hurdles related to living in a digital age.

“We do have to be careful in younger individuals who are raised in the digital world, where analog clocks are few and far between. An inability to draw a clock, in this case, may simply be due to never having learned to read an analog clock in the first place.”

If you believe you have symptoms of schizophrenia, talk with your doctor or therapist about getting a diagnosis.

Schizophrenia myths and facts

Many misconceptions persist about schizophrenia. Receiving a diagnosis can feel overwhelming, but learning the truth can help.

Myth 1: Schizophrenia means you have multiple personalities.

Fact 1: Schizophrenia can feature auditory hallucinations, but multiple personalities are a component of dissociative identity disorder, not schizophrenia.

Myth 2: People living with schizophrenia are violent.

Fact 2: People with schizophrenia are actually more likely to experience violence than commit it, according to a 2021 research review.

Learn more about this myth.

Myth 3: You won’t be able to hold a job with schizophrenia.

Fact 3: Treatment can improve the symptoms of schizophrenia and often involves the use of programs and professionals specifically oriented to help you maintain independent functions, like employment.

Learn more about the best jobs for people with schizophrenia.

Was this helpful?

The CDT in schizophrenia is a tool to help evaluate cognitive impairment. It can help assess executive functions, memory, and perception.

Not passing a CDT with flying colors doesn’t mean you have schizophrenia. It suggests you have a detectable level of cognitive decline, but it can’t indicate the underlying cause.

While some patterns seen in the CDT may be more specific to schizophrenia, experts don’t consider the test an essential part of the diagnostic process.