The "dementia epidemic" that was previously forewarned may be overstated after researchers find the number of people with the condition is stabilizing in some Western European countries.
The first epidemiological studies examining the effects of dementia were started in the 1980s but, to this day, still continue to shape the development of health policies in governments.
Leading researchers from various institutions across Europe sought to investigate if the data collected from these studies is still relevant to today's world.
Lead author Prof. Carol Brayne, from the University of Cambridge in the UK, explains:
"These old studies support the idea of a continuing 'dementia epidemic' but are now out of date because of changes in life expectancy, living conditions, and improvements in health care and lifestyle."
The results - published in The Lancet Neurology - saw data collected from five large epidemiological studies that focused on the rate of dementia occurrence. The studies analyzed were all based in Europe and were taken from Sweden, the UK, the Netherlands and Spain.
By utilizing consistent research methods and diagnostic criteria, researchers compared the rate of dementia occurrence across two periods of time.
The results suggest the prevalence (percentage of the population diagnosed) and incidence (number of new cases over time) of dementia in specific age groups are falling across time and generations.
Four of the five studies analyzed showed non-significant changes in overall dementia occurrences over the past year 20-30 years.
In the UK, there was a significant reduction of 22% in the prevalence of dementia for people aged 65 years and older compared with earlier predicted figures. This drop has resulted in the estimated number of patients diagnosed with the condition to stabilize.
There was also a significant reduction in dementia prevalence for individuals aged 65 years and older in Spain, with a drop of 43% between 1987-1996.
Data from the other studies in Sweden and the Netherlands demonstrate that age-specific incidences of dementia are also falling.
Improvements in prevention and treatment
According to Prof. Brayne, the results indicate dementia has fallen in conjunction with improvements in protective factors against the disease and reductions in risk factors. She explains:
"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."
Despite these encouraging results that dementia occurrences have decreased, she warns that the challenge of providing care for the disease will remain.
Co-author Yu-Tzu Wu, from the University of Cambridge, echoes her view. She says:
"It is important to remember that the number of people over age 85 is the fastest growing age demographic, with about 40% currently estimated to be affected by dementia."
The article concludes by speaking of "the potential long-term benefits of national policies related to education, social determinants of health affecting inequalities, and health behaviors for future generations."
The evidence also reinforces the potential for preventive strategies to reduce the risk of developing dementia compared with the "overemphasis on pharmaceutical interventions in late life" to treat the condition.
'Fear of dementia has been engendered in parallel'
Wu told Medical News Today that although awareness and education of the issue are essential, it is important not to overstate the danger of the disease:
"Awareness and education are important for public health practice. However, fear of dementia has been engendered in parallel, to some extent through attention the topic has raised and the tone of that attention."
Over the past decade, the diagnosis of dementia has also changed. However, Wu said that this may not necessary mean an increase of dementia cases. She told MNT:
"There will have been a large increase in dementia recorded in routine records because of the increased attention and awareness, but this does not necessarily reflect a change in the underlying dementia in the population. In particular, the diagnostic criteria (the definition of dementia) has changed over the last decades and tend to include mild/very mild dementia cases that might not progress to a severe stage."
The onset of dementia remains a major global health issue. Alzheimer's disease is currently the most common form of dementia, accounting for around 60-80% of cases.