Researchers at the University of Michigan used data from the Health and Retirement Study, a US-wide study that has been collecting information on the health and economic wellbeing of thousands of over-50s since 1990. The team analysed information from 10,546 people over the age of 65 who took part in the study’s 2000 wave of research, and 10,511 people from its 2012 wave.
In each wave of the study, participants took part in a survey about their health that included tests of memory and thinking skills, which were used to determine whether people had dementia. The results showed that in 2000, 11.6% of the group had a form of dementia, while in 2012, the prevalence of dementia had fallen to 8.8%.
The team also looked for factors that may be linked to dementia risk in each study group. Following previous studies that showed falling or stabilising dementia prevalence in some countries, researchers have suggested that this changing trend could be partly down to improved cardiovascular health for younger generations. However, data from the latest study showed that the 2012 group tended to report having worse cardiovascular health than those who took part in the study in 2000, with higher rates of obesity, diabetes and high blood pressure – suggesting that other factors also played a part in the decline in dementia prevalence.
Further analysis showed that people with more education were less likely to have dementia, and that the average number of years of education for each group had increased between 2000 and 2012.
Hilary Evans, Chief Executive of Alzheimer’s Research UK, said:
“These results give us cause to be optimistic, but we should be mindful that as our leading cause of death, dementia is still our greatest medical challenge. This useful study adds to emerging evidence suggesting that dementia prevalence may be either declining or stabilising in parts of western Europe and the US, but there are still many unanswered questions. We need to understand what is driving this apparent change in dementia risk if we are to harness this knowledge to provide crucial public health advice.
“The challenge for research is to provide better evidence about the actions the public and policymakers can take to reduce the nation’s dementia risk, which is why Alzheimer’s Research UK is increasing investment in this area. In the meantime, the best evidence currently suggests that maintaining a healthy lifestyle and staying mentally active may help lower the risk of dementia.
“While these findings present a positive picture, we must not forget that there are still huge numbers of people living with dementia and with an ageing population, the number of people developing the condition is still expected to rise. We urgently need to invest in research if we are to find the treatments and preventions that are so desperately needed.”