Risk factors for cardiovascular diseases which include high BP, diabetes, obesity and smoking are believed to play a major role in the likelihood of developing dementia, cognitive decline and Alzheimer's disease.
A new study suggests that people who accumulate these risk factors over time, at a faster pace, have an increased risk of developing Alzheimer's disease dementia or vascular dementia, compared to people whose risk factors remain stable throughout life. The research was published in the April online issue of Neurology, the medical journal of the American Academy of Neurology.
"Our study suggests that having an accelerated risk of cardiovascular disease, quickly accumulating more risk factors like high blood pressure and obesity, is predictive of dementia risk and associated with the emergence of memory decline," said study author Bryn Farnsworth von Cederwald, PhD, of Umea University in Sweden. "As a result, earlier interventions with people who have accelerated cardiovascular risks could be an effective way to help prevent further memory decline in the future."
The study looked at 1,244 people with an average age of 55 who were considered healthy in terms of cardiovascular health and memory skills at the start of the study. Participants were given memory tests, health examinations, and completed lifestyle questionnaires every five years for up to 25 years.
Of all participants, 78 people, or 6 per cent, developed Alzheimer's disease dementia during the study and 39 people, or 3 per cent, developed dementia from vascular disease.
Cardiovascular disease risk was determined by using the Framingham Risk Score which predicts the 10-year risk of a cardiovascular event. It looks at factors including a person's age, sex, body mass index (BMI), blood pressure and whether they smoke or have diabetes. Participants started the study with an average 10-year risk of between 17 per cent and 23 per cent.
Researchers determined who had an accelerated cardiovascular disease risk by comparing participants to the average progression of cardiovascular disease risk.
Researchers found that cardiovascular disease risk remained stable in 22 per cent of participants, increased moderately over time in 60 per cent, and rose at an accelerated pace in 18 per cent of people.
People in the study with stable cardiovascular disease risk had an average 20 per cent risk of a cardiovascular event over 10 years throughout the study, while those with a moderately increased risk went from 17 per cent to 38 per cent over the course of the study and those with an accelerated risk went from a 23 per cent to 62 per cent increased risk by the end of the study.
Researchers determined that when compared to people with stable cardiovascular disease risk, people with an accelerated cardiovascular disease risk had a three to six times greater chance of developing Alzheimer's disease dementia and a three to four times greater risk of developing vascular dementia. They also had up to 1.4 times greater risk of memory decline in middle age.
"Several risk factors were elevated in people with an accelerated risk, indicating that such acceleration may come from an accumulation of damage from a combination of risk factors over time," said Farnsworth von Cederwald. "Therefore, it is important to determine and address all risk factors in each person, such as reducing high blood pressure, stopping smoking and lowering BMI, rather than just address individual risk factors in an effort to prevent or slow dementia."
A limitation of the study was the inability to determine whether the decline leading to dementia is initiated by an accelerated cardiovascular disease risk. Farnsworth von Cederwald said it cannot be ruled out that other factors may also contribute, so more research is needed.
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