Summary: A new study reports the number of people living with dementia globally more than doubled between 1990 and 2016. By 2050, more than 100 million people could be living with dementia related diseases, researchers report. The study suggests people could avoid the risk of developing dementia by maintaining a healthy weight, eating a healthy diet and monitoring blood pressure.

Source: University of Melbourne.

The number of people living with dementia globally more than doubled between 1990 and 2016 from 20.2 million to 43.8 million, prompting researchers to call for more preventative action.

A new paper published in The Lancet Neurology also found that 22.3 per cent of healthy years lost due to dementia in 2016 were due to modifiable risk factors.

Prepared by academics across multiple institutions and led by the University of Melbourne and the University of Washington, the paper looked at the global, regional and national burden of Alzheimer’s Disease and other dementias from 1990-2016.

The systematic analysis of the Global Burden of Disease Study 2016 found dementia was more common at older ages, with the prevalence doubling every five years over age 50. There was also significant potential for prevention.

“In our study, 22.3 per cent (11.8 – 35.1 per cent) of the total global disability-adjusted life years lost due to dementia in 2016 could be attributed to the four modifiable risk factors – being overweight, high blood sugar, consuming a lot of sugar sweetened beverages and smoking,” the authors said.

University of Melbourne lead author Professor Cassandra Szoeke said even more risk factors would be explored in the new data collection.

“But already the importance of these risks in allowing us to prevent or delay dementia is clear,” she said. “The paper noted that changes in risk factor exposure over time as we become healthier might account for several cohort studies documenting a reduction in age-specific incidence rates in their study populations.”

Because dementia develops over at least 20 to 30 years before it is diagnosed, Professor Szoeke said studies needed to investigate cognition over 20 to 30 years to determine when and for how long intervention was needed to prevent disease.

She said most randomised controlled trials lasted one to five years and the necessary 30-year longitudinal studies were rare.

“In addition, when you look over decades there are so many exposures that impact on our health, you need to account for all these things or you could miss a factor that is crucial in the development of disease,” she said.

Professor Szoeke said by 2050 the number of people living with dementia could be around 100 million. “The paper states that to support our community, we will need a larger workforce of trained health professionals as well as planning and building facilities and community-based services which support improved quality of life and function,” she said.

“We need to enhance the quality of life and function of people living with cognitive impairment and focus on preventing further cognitive decline. This will need a co-developed community wide approach with well-developed services and an even greater network of trained health professionals.

“Chronic diseases are becoming the leading causes of death and disability worldwide, and whilst we continue to work daily on new therapies to target disease, at home we really need to focus more on the health choices that we know extend both disease-free and disability-free survival.”

About this neuroscience research article

Funding: Bill & Melinda Gates Foundation funded the study.

Source: Cheryl Critchley – University of Melbourne

Publisher: Organized by NeuroscienceNews.com.

Image Source: NeuroscienceNews.com image is credited to University of Melbourne.

Original Research: Open access research for “Global, regional, and national burden of Alzheimer’s disease and other dementias, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016” by GBD 2016 Dementia Collaborators in Lancet Neurology. Published November 26 2018

doi:10.1016/S1474-4422(18)30403-4

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[cbtabs][cbtab title=”MLA”]University of Melbourne”The Number of People with Dementia Has Doubled in Sixteen Years.” NeuroscienceNews. NeuroscienceNews, 4 January 2019.

<https://neurosciencenews.com/dementia-cases-doubled-10435/>.[/cbtab][cbtab title=”APA”]University of Melbourne(2019, January 4). The Number of People with Dementia Has Doubled in Sixteen Years. NeuroscienceNews. Retrieved January 4, 2019 from https://neurosciencenews.com/dementia-cases-doubled-10435/[/cbtab][cbtab title=”Chicago”]University of Melbourne”The Number of People with Dementia Has Doubled in Sixteen Years.” https://neurosciencenews.com/dementia-cases-doubled-10435/ (accessed January 4, 2019).[/cbtab][/cbtabs]

Abstract

Global, regional, and national burden of Alzheimer’s disease and other dementias, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016

Background

The number of individuals living with dementia is increasing, negatively affecting families, communities, and health-care systems around the world. A successful response to these challenges requires an accurate understanding of the dementia disease burden. We aimed to present the first detailed analysis of the global prevalence, mortality, and overall burden of dementia as captured by the Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study 2016, and highlight the most important messages for clinicians and neurologists.

Methods

GBD 2016 obtained data on dementia from vital registration systems, published scientific literature and surveys, and data from health-service encounters on deaths, excess mortality, prevalence, and incidence from 195 countries and territories from 1990 to 2016, through systematic review and additional data-seeking efforts. To correct for differences in cause of death coding across time and locations, we modelled mortality due to dementia using prevalence data and estimates of excess mortality derived from countries that were most likely to code deaths to dementia relative to prevalence. Data were analysed by standardised methods to estimate deaths, prevalence, years of life lost (YLLs), years of life lived with disability (YLDs), and disability-adjusted life-years (DALYs; computed as the sum of YLLs and YLDs), and the fractions of these metrics that were attributable to four risk factors that met GBD criteria for assessment (high body-mass index [BMI], high fasting plasma glucose, smoking, and a diet high in sugar-sweetened beverages).

Findings

In 2016, the global number of individuals who lived with dementia was 43·8 million (95% uncertainty interval [UI] 37·8–51·0), increased from 20.2 million (17·4–23·5) in 1990. This increase of 117% (95% UI 114–121) contrasted with a minor increase in age-standardised prevalence of 1·7% (1·0–2·4), from 701 cases (95% UI 602–815) per 100 000 population in 1990 to 712 cases (614–828) per 100 000 population in 2016. More women than men had dementia in 2016 (27·0 million, 95% UI 23·3–31·4, vs 16.8 million, 14.4–19.6), and dementia was the fifth leading cause of death globally, accounting for 2·4 million (95% UI 2·1–2·8) deaths. Overall, 28·8 million (95% UI 24·5–34·0) DALYs were attributed to dementia; 6·4 million (95% UI 3·4–10·5) of these could be attributed to the modifiable GBD risk factors of high BMI, high fasting plasma glucose, smoking, and a high intake of sugar-sweetened beverages.

Interpretation

The global number of people living with dementia more than doubled from 1990 to 2016, mainly due to increases in population ageing and growth. Although differences in coding for causes of death and the heterogeneity in case-ascertainment methods constitute major challenges to the estimation of the burden of dementia, future analyses should improve on the methods for the correction of these biases. Until breakthroughs are made in prevention or curative treatment, dementia will constitute an increasing challenge to health-care systems worldwide.

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