Dementia Rates Leveling Off, Despite Aging Population.

Despite an aging population, a number of recent studies indicate a stable or declining prevalence and incidence of dementia—findings that highlight the need for action “to address factors that determine both healthy and unhealthy aging” and that reduce inequities, says a new paper co-authored by a School of Public Health researcher.

Writing in the journal Nature Reviews Neurology, a research team that includes Alexa Beiser, professor of biostatistics, reviewed findings from 14 studies that investigated trends in dementia prevalence and incidence in the US and other countries. The review found that dementia is declining in some countries, and that the number of people with dementia can remain stable despite the population aging.

Identifying factors that contribute to these reductions, such as improvements in living conditions and better access to education and quality health care, should become a “major priority,” the authors say.

All five studies that examined trends in incidence suggest a decrease in the rate of dementia in the total population across different groups and time periods, the review says. Similarly, most of the nine population-based studies examining prevalence reported stable or declining rates over time.

“The primary evidence from western countries discussed in this review suggests a reduction in the risk of developing dementia and improved health in old age across generations,” the authors say. Possible explanations include higher educational levels, declines in chronic diseases such as stroke, heart disease and hypertension, and social factors that might improve cognitive health over a person’s lifetime.

According to estimates from the World Alzheimer Report 2015, nearly 47 million people worldwide have dementia, and that number is expected to grow to more than 74 million by 2030 and more than 131 million by 2050. The G8 dementia summit in 2013 and the WHO Ministerial Conference in 2015 resulted in calls for global action against dementia, including a goal to identify a cure or disease-modifying therapy by 2025.

“Only an integrated approach that incorporates life course health and brings together many disciplines underpinned by neuroscience and population-based epidemiological studies can provide the robust evidence required to understand the observed changes,” the study says.

The study was led by Carol Brayne of the Department of Public Health and Primary Care of the Cambridge Institute of Public Health in the UK.

—Lisa Chedekel