Prevention research is about identifying factors which are linked to the development of dementia, other factors which may be protective against developing dementia, and finding ways of facilitating healthy brain ageing. Researchers often do this by comparing large groups of people who go on to develop dementia, and those who do not, according to things such as clinical findings, lifestyles and drug prescription in the years and even decades before the onset of dementia.
Some forms of this research include retrospective cross-sectional studies, longitudinal studies, and intervention studies.
Cross sectional studies: These studies compare records of lifestyle, demographic and health related information in those who have dementia and people who do not have dementia. By doing this, researchers can analyse what factors are associated with the development of dementia, and what factors seem to be protective of developing dementia.
Longitudinal studies: These studies observe a cohort of people without dementia and follow them up at defined intervals. Some studies select volunteers who are representative of the general population. Other studies select people who are at an elevated risk of dementia based on family history, genetic information, or those who have mild cognitive impairment.
Intervention studies: Some studies may prescribe an intervention or modification to volunteers’ lifestyle, such as exercise, dietary changes or drugs, to reduce the risk of developing dementia. These modifications are identified as being protective in previous studies. Researchers typically select a cohort of people who do not have dementia and are either healthy or are at an elevated risk. They may randomly assign people to the intervention. They then look at whether the intervention made a difference in terms of the number of people who go on to be diagnosed with dementia at follow up.
Prevention research is a major focus of dementia research. Since there are currently no treatments that can stop the progression of dementia, prevention research is of tremendous importance. Whilst we can’t change ‘unmodifiable’ risk factors such as our genetics or age, research has identified many ‘modifiable’ risk factors for developing dementia – meaning that there are many things we can do earlier in life to reduce our risk.
Researchers now believe that reducing mid-life body mass index, controlling high blood pressure and diabetes, and reducing cholesterol during mid-life will lower your risk of developing dementia in later life. There is also strong evidence for other protective factors including regular exercise, avoiding head injury, not smoking, moderate coffee intake, adequate sleep, adequate B vitamins and reducing saturated fat intake. We also know that education, keeping mentally active and socialising can help to delay cognitive decline after the onset of dementia.
Researchers need large numbers of people to perform high-quality and reliable prevention studies. A large sample size may include thousands of people. Some of the common selection criteria for these studies may include:
A 2 year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial (The Lancet; Ngandu et al., 2015)
The FINGER study is an ongoing study conducted in Finland. The purpose is to determine if a comprehensive lifestyle intervention for people with an elevated risk of dementia could improve cognitive ability and reduce the incidence of dementia.
It recruited 1260 Finnish people with an average age of 69. To be eligible for recruitment, people were required to be at an elevated risk of both cardiovascular disease and dementia based on their age, sex, education, blood pressure, body-mass index, cholesterol, and physical activity. The rationale for these selection criteria was that people with elevated cardiovascular risk factors also have a higher incidence of dementia. In addition, researchers selected for people with cognitive test scores that were average, or slightly below average. People were excluded from the study if there was any clinical suspicion of dementia or very low scores on cognitive tests.
Participants in the intervention group were randomly assigned to either a control group or an intervention group. The control group received regular health advice. The intervention group undertook a comprehensive lifestyle modification with four components:
The researchers found that after two years, people in the intervention group performed significantly better on cognitive tests. Researchers will follow up both groups after 7 years, to determine if the intervention is associated with a lower incidence of dementia.
Since the original FINGER study researchers around the globe have come together to share experiences, harmonise their approaches to collect data and plan international collaborations for the prevention of cognitive impairment and dementia.
See World Wide FINGERS http://wwfingers.com/