A Swedish research team seeking a reliable way to determine who is most at risk of dying after stroke discovers that a simple drawing test may be a good predictor.
The team, lead by Dr. Bernice Wiberg from Uppsala University in Sweden, looked at participants in the Uppsala Longitudinal Study of Adult Men, which has tracked various heart disease and stroke risk factors in 2,322 men since age 50. For the current study, the researchers included more than 900 of the original participants, monitoring them from 1991 to 2006, starting when the men were about 70. None of the men had been diagnosed with stroke at the start of the follow-up.
The participants got a full medical exam and also underwent assessments of cognitive function. They completed a drawing test called the Trail Making Test (TMT) as well as the mini mental state exam (MMSE), a widely used screening test for dementia. The TMT involves drawing lines as fast as possible between numbers or letters in ascending order; your score is the number of seconds it takes you to complete the task. The MMSE rates performance on general cognitive tasks involving orientation, memory and numeracy.
During the 14-year follow-up period, 155 men had a stroke. Of these men, more than half died within 2.5 years, with 22 dying within a month of their stroke. The researchers found that those who had done poorly on their TMT were more likely to die. That result held even after the researchers took into account other risk factors like old age, high blood pressure and education level.
Men whose scores on the TMT were the bottom 30% were three times more likely to die after their stroke than those who scored in the upper 30%. There was no similar association found for MMSE test scores.
In previous research, Wiberg found that the TMT was a strong predictor of stroke itself. These new findings take the association a step further by linking the test scores to risk of stroke death. “I was surprised during the first study that the results from [TMT] were such a strong predictor of stroke. I was not surprised that it was also related to mortality after stroke, but I had not suspected such a strong relation,” says Wiberg.
Wiberg and her colleagues theorize that the TMT picks up on hidden cognitive impairments caused by cerebrovascular disease that has yet to produce clear symptoms, but still has damaging effects on executive function.
The TMT is readily available and easy to administer, which the authors say could help doctors improve stroke information for patients and their families. “With a simple paper-and-pen test you have a tool to predict risk of stroke and also mortality after stroke,” says Wiberg.
Patients should remember that there are many other major risk factors for stroke that can be controlled through behavioral changes or medication, including high blood pressure and cholesterol, diabetes, smoking, lack of exercise and obesity.
The study was published in the online journal BMJ Open.