The risk of dementia may be falling due to improved education and living conditions, and better prevention and treatment of vascular diseases, highlighting the need for policies to improve to create a healthier lifestyle.
In a Policy View published in The Lancet Neurology journal, a group of leading experts on the epidemiology of dementia state that the number of people with dementia in some Western European countries is stabilising despite population ageing, in direct contrast to the “dementia epidemic” reported in some recent studies.
The Policy View discusses data from five large epidemiological studies done in Sweden, the Netherlands, the UK, and Spain that compare dementia occurrence in old people across two periods of time using the same methods of diagnosing dementia in the same regions. The findings suggest that prevalence (i.e., the percentage of the population with dementia) and incidence (the number of new dementia cases over a given time) of dementia in specific age groups are falling across time and generations.
Estimates of the proportion of dementia cases within countries are needed to plan for the care of people suffering with dementia, yet much of the evidence used at both national and local levels (e.g., the UK’s NHS primary care targets) is based on research started in the 1980s. Carol Brayne, lead author and Professor of Public Health Medicine at the Cambridge Institute of Public Health (CIPH), University of Cambridge in the UK, says:
“These old studies support the idea of a continuing ‘dementia epidemic’, but are now out of date because of changes in life expectancy, living conditions, and improvements in health care and lifestyle,”
Findings from four of the five studies analysed in the Policy View showed non-significant changes in overall dementia occurrence over the past 20 to 30 years. The UK study showed a significant reduction (about 22%) in overall prevalence in people aged 65 years in 2011 than the predicted estimates in 1990, resulting in stabilisation of estimated numbers of people with dementia.
“The suggested decrease in dementia occurrence coincides with improvements in protective factors (such as education and living conditions) for dementia and a general reduction in risk factors (such as vascular diseases) over recent decades,” explains Brayne. “Incidence and deaths from major cardiovascular diseases have decreased in high-income countries since the 1980s. We are now potentially seeing the results of improvements in prevention and treatment of key cardiovascular risk factors such as high blood pressure and cholesterol reflected in the risk of developing dementia.”
According to the researchers, although the decrease in dementia occurrence is a positive sign, dementia care will remain a crucial challenge for many years because of population ageing.