Cardiovascular health is increasingly becoming a major risk factor for dementia, new research suggests, while other known risk factors like smoking and education level have become less significant.
More than 5 million Americans over the age of 65 live with dementia, according to 2014 data from the U.S. Centers for Disease Control and Prevention. Dementia comes in different forms—the most common form is Alzheimer's disease—and is characterized by an impaired ability to remember, think and make decisions.
Exactly what causes dementia isn't entirely clear, but a range of genetic and environmental risk factors have been associated with the condition. Among these are hypertension, obesity, diabetes, education and smoking. However, a new study from University College London in the U.K. has found that the proportion of dementia cases attributable to each of these risk factors has varied over time.
In the study, published in the journal The Lancet Public Health, the UCL team analyzed 27 research papers from around the world with data collected between 1947 and 2015. During their analysis, the team extracted data from each paper about dementia risk factors and the proportion of dementia cases that were attributable to each one.
The team found that, over time, lower levels of education and smoking had become less common, whereas rates of obesity, diabetes and cardiovascular disease had increased over time, as had made contributions to dementia risk.
"Hypertension contributes the most to dementia risk at the moment in many of the studies, with the other cardiovascular risk factors contributing an increasing amount over time," lead author Naaheed Mukadam, a professor in psychiatry at UCL, told Newsweek.
"Cardiovascular risk factors may have contributed more to dementia risk over time, so these deserve more targeted action for future dementia prevention efforts."
Education was one of the most important risk factors for dementia throughout the study period. However, over time it has seen a decline in prevalence and thus its contribution to dementia risk.
"Our results show that levels of education have increased over time in many higher income countries, meaning that this has become a less important dementia risk factor," Mukadam said. "Meanwhile, smoking levels have also declined in Europe and the USA as it has become less socially acceptable and more expensive."
Previous research from the university demonstrated that 40 percent of dementia cases could be delayed or prevented by modifying these key lifestyle-related risk factors, so understanding their respective contributions to disease prevalence is important for effective intervention.
"These patterns suggest that population-level interventions could significantly impact the occurrence of dementia risk factors, and governments should consider implementing schemes such as worldwide policies of education, and restrictions on smoking," Mukadam said.