International research led by NUI Galway has identified the most important risk factors for dementia in middle-aged and older people.
The study, which also involved researchers in Boston University, and the University of Texas Health Sciences Center in San Antonio, examined data from 5,000 people to assess potential predictors for loss of cognitive function.
The most important vascular risk factors for dementia were:
at age 55 – high blood pressure and diabetes mellitus
at age 65 – cardiovascular disease (e.g. heart attacks or angina)
at ages 70 and 75 – diabetes mellitus and previous stroke
at age 80 – diabetes mellitus, previous stroke and not taking blood-pressure lowering medication
The study was published today in Neurology®, the medical journal of the American Academy of Neurology and was led by Professor Emer McGrath, Associate Professor at the College of Medicine Nursing and Health Sciences at NUI Galway and Consultant Neurologist at Saolta University Hospitals.
The researchers measured risk factors for dementia, including age, sex, blood pressure, use of blood pressure lowering medication, a history of cardiovascular disease, atrial fibrillation and diabetes mellitus. The patient data was sourced from thousands of people who took part in the US-based Framingham Heart Study.
Risk factors were measured at mid-life (i.e. 55) and again at ages 65, 70, 75 and 80 years-old.
Professor McGrath said: “Accurately predicting a person’s future risk of dementia could inform personalised approaches to risk factor and lifestyle modification to help reduce that risk. However, predicting this is challenging as the relationship between dementia and vascular risk factors such as diabetes, blood pressure, heart disease and stroke varies with age.”
“We found that people who had diabetes at the age of 55 were four times more likely to go on to develop dementia than people who did not have diabetes at that age”
“People with heart disease at age 65 were nearly twice as likely to later develop dementia as those who did not have a heart condition, while people with a stroke at age 70 were over three times as likely to develop dementia compared to those with no stroke”.
“Our study shows that predicting a person’s risk of dementia needs to be very much tailored towards the individual, taking into account their age, sex, vascular risk factors and evidence of organ damage, such as previous heart attack or stroke.
“Based on this research, we should probably be looking at more individualised, age-specific dementia risk scores, rather than a one-size-fits-all approach to dementia risk prediction.”
According to the Alzheimer’s Association of Ireland, 64,000 people are living with dementia in Ireland. It is estimated that the number of people with the condition will more than double in the next 25 years to more than 150,000 by 2045.
Professor McGrath said: “Our research has important implications for dementia prevention at a population-level. Controlling vascular risk factors such as high blood pressure and diabetes mellitus, adopting healthier eating habits and following an active lifestyle, particularly at the early to mid-life stage, could significantly reduce a person’s risk of developing dementia down the line.”
Professor Sudha Seshadri, co-author of the study, is Professor of Neurology and Director of the Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Diseases at the University of Texas Health Sciences Center, San Antonio and Senior Investigator with the Framingham Heart Study.
Professor Seshadri said “At younger ages, vascular risk factors like blood pressure seemed more important. At older ages, the effects of long-standing exposure to risk factors in the form of organ damage, such as stroke, seemed to best predict risk of dementia.”
“Diabetes has been identified as one of seven risk factors responsible for up to one-third of cases of Alzheimer’s disease dementia and represents an important modifiable target for dementia prevention at a population-level.”