Beverly Shipley, a psychology department doctor from the Edinburgh University conducted a survey in which she investigated mental agility of over 6,400 people from all over Britain in the last twenty years.
The study lasted for 21 years, included people aged 18-99 who first got tested back in 1984-85. From 1985 until 2005 when the study ended, 1,550 of the participants died.

The study results reveal that people who had slower reaction times, poorer memory and poor visual-spatial awareness had bigger chances of dying from respiratory and cardiovascular diseases. Even after putting other risks factors for heart disease into the picture like physical activity, blood pressure, body mass index and smoking, the results were still the same.

Dr. Beverly Shipley suggests that differences in mental ability could represent a risk factor for some vascular diseases. The surprising was the fact that there was no difference between younger and older adults and that there was the same link between cognition and heart disease mortality. The reason was, however, not found.
It was found that those people with lower than average mental agility had 10% more chances of suffering from a heart disease. It is thought that the human reaction time shows how things are wired within human body.