People with low scores on a test of executive function, the higher-level thinking skills used to reason, problem solve and plan, may be at higher risk of heart attack or stroke, according to a new study published in the August 5, 2015, online issue of Neurology®, the medical journal of the American Academy of Neurology.

"These results show that heart and brain function are more closely related than appearances would suggest," said study author Behnam Sabayan, MD, PhD, of Leiden University Medical Center in Leiden, the Netherlands. "While these results might not have immediate clinical translation, they emphasize that assessment of cognitive function should be part of the evaluation of future cardiovascular risk."

The study involved 3,926 people with an average age of 75 and without a history of heart attacks or strokes. All of the people involved had either a history of heart disease or an increased risk of heart disease from high blood pressure, diabetes or smoking. The people were also free of dementia.

Four tests were used to evaluate the participants' high-level thinking skills at the beginning of the study. The participants were then placed in groups of "low," "medium" and "high" based on the results. The participants were then followed for an average of three years to see who developed heart attacks or strokes. During that time, there were 375 heart attacks and 155 strokes, which is a rate of 31 heart attacks per 1,000 person-years and 12 strokes per 1,000 person-years.

People in the lowest group of executive function thinking skills were 85 percent more likely to have a heart attack than those in the highest group. A total of 176 of the 1,309 people with low scores had heart attacks, compared with 93 of the 1,308 people with high scores, which translates to a rate of 44 heart attacks per 1,000 person-years for people with low scores compared with 22 heart attacks per 1,000 person-years for people with high scores.

For strokes, people with low scores had a 51 percent higher risk of stroke. There were 69 strokes among those with those with low scores, compared with 48 strokes among those with high scores.

"Performance on tests of thinking and memory are a measure of brain health. Lower scores on thinking tests indicate worse brain functioning. Worse brain functioning in particular in executive function could reflect disease of the brain vascular supply, which in turn would predict, as it did, a higher likelihood of stroke. And, since blood vessel disease in the brain is closely related to blood vessel disease in the heart, that's why low test scores also predicted a greater risk of heart attacks," said Sabayan. "We acknowledge that even though the results were statistically significant, the risks were small."