Projected Dementia Epidemic Averted?

Megan Brooks

September 02, 2015

Despite an aging population, dementia cases may be leveling off in western Europe thanks to better education and living conditions and greater attention to vascular disease, say the authors of a new paper.

Current estimates of the number of dementia cases in western European countries are based on old studies from the 1980s, they note in a Policy View article published online August 21 in The Lancet Neurology.

"These old studies support the idea of a continuing 'dementia epidemic,' but are now out of date because of changes in life expectancy, living conditions, and improvements in health care and lifestyle," lead author Carol Brayne, MD, from the University of Cambridge, United Kingdom (UK), said in a news release.

To get a more up-to-date picture, she and her colleagues synthesized evidence from five large cohort studies from Sweden (Stockholm and Gothenburg), the Netherlands (Rotterdam), the UK (England), and Spain (Zaragoza) that have compared dementia occurrence over time.

Prevention Working

Findings from four of the studies show nonsignificant changes in overall occurrence of dementia over the past 20 to 30 years, they report.

The UK study, which was powered and designed explicitly to detect change across generations, points to a significant decline in overall dementia prevalence of about 22% (P = .003) in people aged 65 years in 2011 than predicted estimates from 1990, leading to a substantial stabilization of estimated numbers of dementia cases, they say.

The study from Spain suggests a significant decline in dementia prevalence of 43% (P = .0002) in men aged 65 years and older between 1987 and 1996. The studies from Sweden and the Netherlands point to nonsignificant reductions in age-specific incidence of dementia in these regions.

"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," Dr Brayne noted in the news release.

"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," she added.

While the potential leveling off in dementia cases is a positive sign, dementia care will remain a crucial challenge for years to come because of the aging population, the researchers note. "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," University of Cambridge coauthor Yu-Tzu Wu, MSc, said in the release.

"Our up-to-date evidence," added Dr Brayne, "suggests a relatively optimistic picture of possible future trends in dementia occurrence and strengthens the need to shift more of our societal and research focus to primary prevention across the life course, with a rebalancing from what could be seen as the current overemphasis on diagnostics and drug interventions for dementia (which detect early or later assumed pathology).

"Policies which address determinants of health in earlier life stages and enhance cognitive reserve for populations may have the greatest long term impact on reduction of dementia risk at given ages in later life as well as on population health more generally."

The authors have disclosed no relevant financial relationships.

Lancet Neurol. Published online August 21, 2015. Abstract

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