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Clock drawing cognitive test should be done routinely in patients with high blood pressure

Psychiatric Disorders and Heart Disease
Cardiovascular Disease in the Elderly


Munich, Germany – 27 Aug 2018: A clock drawing test for detecting cognitive dysfunction should be conducted routinely in patients with high blood pressure, according to research presented today at ESC Congress 2018. (1)

Patients with high blood pressure who have impaired cognitive function are at increased risk of developing dementia within five years. Despite this known link, cognitive function is not routinely measured in patients with high blood pressure.

“The ability to draw the numbers of a clock and a particular time is an easy way to find out if a patient with high blood pressure has cognitive impairment,” said study author Dr Augusto Vicario of the Heart and Brain Unit, Cardiovascular Institute of Buenos Aires, Argentina. “Identifying these patients provides the opportunity to intervene before dementia develops.”

The Heart-Brain Study in Argentina evaluated the usefulness of the clock drawing test compared to the Mini-Mental State Examination (MMSE) to detect cognitive impairment in 1,414 adults with high blood pressure recruited from 18 cardiology centres in Argentina. The average blood pressure was 144/84 mmHg, average age was 60 years, and 62% were women.

For the clock drawing test, patients were given a piece of paper with a 10 cm diameter circle on it. They were asked to write the numbers of the clock in the correct position inside the circle and then draw hands on the clock indicating the time "twenty to four". Patients were scored as having normal, moderate, or severe cognitive impairment (see figure 1). The MMSE has 11 questions and produces a score out of 30 indicating no (24–30), mild (18–23), or severe (0–17) cognitive impairment.

The researchers found a higher prevalence of cognitive impairment with the clock drawing test (36%) compared to the MMSE (21%). Three out ten patients who had a normal MMSE score had an abnormal clock drawing result. The disparity in results between the two tests was greatest in middle aged patients (see figure 2).

Dr Vicario said: “Untreated high blood pressure silently and progressively damages the arteries in the subcortex of the brain and stops communication between the subcortex and frontal lobe. This disconnect leads to impaired ‘executive functions’ such as planning, visuospatial abilities, remembering details, and decision-making. The clock drawing test is known to evaluate executive functions. The MMSE evaluates several other cognitive abilities but is weakly correlated with executive functions.”

He continued: “Our study suggests that the clock drawing test should be preferred over the MMSE for early detection of executive dysfunction in patients with high blood pressure, particularly in middle age. We think the score on the clock drawing test can be considered a surrogate measure of silent vascular damage in the brain and identifies patients at greater risk of developing dementia. In our study more than one-third of patients were at risk.”

Dr Vicario concluded: “The clock drawing test should be adopted as a routine screening tool for cognitive decline in patients with high blood pressure. Further studies are needed to determine whether lowering blood pressure can prevent progression to dementia.”

Figure 1: Normal, moderate, and severe cognitive impairment on the clock drawing test

Vicario figure 1.png

 

Figure 2: Clock drawing test versus Mini-Mental State Examination in patients with high blood pressure

Vicario figure 2.png

 

ENDS

Notes to editor

SOURCES OF FUNDING: None.

DISCLOSURES: None.

References 

(1) The abstract “Utility of the clock drawing test as cognitive screening in patients with arterial hypertension” will be presented during:

 

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About the European Society of Cardiology

The European Society of Cardiology brings together health care professionals from more than 150 countries, working to advance cardiovascular medicine and help people lead longer, healthier lives.

About ESC Congress 2018

ESC Congress is the world’s largest and most influential cardiovascular event contributing to global awareness of the latest clinical trials and breakthrough discoveries. ESC Congress 2018 takes place 25 to 29 August at the Messe München in Munich, Germany. Explore the scientific programme.

 

This press release accompanies both a presentation and an ESC press conference at the ESC Congress 2018. Edited by the ESC from material supplied by the investigators themselves, this press release does not necessarily reflect the opinion of the European Society of Cardiology. The content of the press release has been approved by the presenter.