Forty percent of dementia cases could be prevented or delayed by targeting 12 risk factors throughout life
July 30, 2020
Science Daily/University of Southern California - Health Sciences
Modifying 12 risk factors over a lifetime could delay or prevent 40% of dementia cases, according to an updated report by the Lancet Commission on dementia prevention, intervention and care presented at the Alzheimer's Association International Conference (AAIC 2020).
Twenty-eight world-leading dementia experts added three new risk factors in the new report -- excessive alcohol intake and head injury in mid-life and air pollution in later life. These are in addition to nine factors previously identified by the commission in 2017: less education early in life; mid-life hearing loss, hypertension and obesity; and smoking, depression, social isolation, physical inactivity and diabetes later in life (65 and up).
"We are learning that tactics to avoid dementia begin early and continue throughout life, so it's never too early or too late to take action," says commission member and AAIC presenter Lon Schneider, MD, co-director of the USC Alzheimer Disease Research Center's clinical core and professor of psychiatry and the behavioral sciences and neurology at the Keck School of Medicine of USC.
Dementia affects some 50 million people globally, a number that is expected to more than triple by 2050, particularly in low- and middle-income countries where approximately two-thirds of people with dementia live, according to the report. Women are also more likely to develop dementia than men.
However, in certain countries, such as the United States, England and France, the proportion of older people with dementia has fallen, probably in part due to lifestyle changes, demonstrating the possibility of reducing dementia through preventative measures, Schneider says.
Schneider and commission members recommend that policymakers and individuals adopt the following interventions:
Aim to maintain systolic blood pressure of 130 mm Hg or less from the age of 40.
Encourage use of hearing aids for hearing loss and reduce hearing loss by protecting ears from high noise levels.
Reduce exposure to air pollution and second-hand tobacco smoke.
Prevent head injury (particularly by targeting high-risk occupations).
Limit alcohol intake to no more than 21 units per week (one unit of alcohol equals 10 ml or 8 g pure alcohol).
Stop smoking and support others to stop smoking.
Provide all children with primary and secondary education.
Lead an active life into mid-life and possibly later life.
Reduce obesity and the linked condition of diabetes.
The report also advocates for holistic, individualized and evidenced-based care for patients with dementia, who typically have more hospitalizations for conditions that are potentially manageable at home and are at greater risk for COVID-19. In addition, it recommends providing interventions for family caregivers who are at risk for depression and anxiety.
The commission members conducted a thorough investigation of all the best evidence in the field, including systematic literature reviews, meta-analyses and individual studies, to reach their conclusions.
https://www.sciencedaily.com/releases/2020/07/200730123651.htm
Weight gain and loss may worsen dementia risk in older people
Study recommends continuous weight control and monitoring of weight changes to prevent dementia development
May 20, 2019
Science Daily/BMJ
Older people who experience significant weight gain or weight loss could be raising their risk of developing dementia, suggests a study from Korea.
Dementia is an important health problem especially with increasing life expectancy and an ageing population. In 2015, there were an estimated 46.8 million people diagnosed with dementia.
Meanwhile, the global prevalence of obesity, which is closely related to cardiometabolic diseases, has increased by more than 100% over the past four decades.
There is existing evidence of a possible association between cardiometabolic risk factors (such as high blood pressure, cholesterol and blood sugar levels) and dementia. However, the association between body mass index (BMI) in late-life and dementia risk remains unclear.
Therefore, a team of researchers from the Republic of Korea set out to investigate the association between BMI changes over a two-year period and dementia in an elderly Korean population.
They examined 67,219 participants aged 60-79 years who underwent BMI measurement in 2002-2003 and 2004-2005 as part of the National Health Insurance Service-Health Screening Cohort in the country.
At the start of the study period, characteristics were measured including BMI, socioeconomic status and cardiometabolic risk factors.
The difference between BMI at the start of the study period and at the next health screening (2004-2005) was used to calculate the change in BMI.
After two years, the incidence of dementia was monitored for an average 5.3 years from 2008 to 2013.
During the 5.3 years of follow-up time, the numbers of men and women with dementia totaled 4,887 and 6,685, respectively.
Results showed that there appeared to be a significant association between late-life BMI changes and dementia in both sexes.
Rapid weight change -- a 10% or higher increase or decrease in BMI -- over a two-year period was associated with a higher risk of dementia compared with a person with a stable BMI.
However, the BMI at the start of the period was not associated with dementia incidence in either sex, with the exception of low body weight in men.
After breaking down the figures based on BMI at the start of the study period, the researchers found a similar association between BMI change and dementia in the normal weight subgroup, but the pattern of this association varied in other BMI ranges.
Cardiometabolic risk factors including pre-existing hypertension, congestive heart failure, diabetes and high fasting blood sugar were significant risk factors for dementia.
In particular, patients with high fasting blood sugar had a 1.6-fold higher risk of developing dementia compared to individuals with normal or pre-high fasting blood sugar.
In addition, unhealthy lifestyle habits such as smoking, frequent drinking and less physical activity in late life were also associated with dementia.
This is an observational study, so can't establish cause, and the researchers point to some limitations, including uncertainty around the accuracy of the definition of dementia and reliance on people's self-reported lifestyle habits, which may not be accurate.
However, the study included a large amount of data and reported various modifiable risk factors of dementia in late life.
As such, the researchers conclude: "Both weight gain and weight loss may be significant risk factors associated with dementia. This study revealed that severe weight gain, uncontrolled diabetes, smoking and less physical activity in late-life had a detrimental effect on dementia development.
"Our results suggest that continuous weight control, disease management and the maintenance of a healthy lifestyle are beneficial in the prevention of dementia, even in later life."
https://www.sciencedaily.com/releases/2019/05/190520190053.htm
Obesity linked with differences in form and structure of the brain
Science Daily/April 23, 2019
Radiological Society of North America
Researchers using sophisticated MRI technology have found that higher levels of body fat are associated with differences in the brain's form and structure, including smaller volumes of gray matter, according to a study published in the journal Radiology. The findings add important information to our understanding of the connection between obesity and negative health consequences such as dementia.
"MRI has shown to be an irreplaceable tool for understanding the link between neuroanatomical differences of the brain and behavior," said study lead author Ilona A. Dekkers, M.D., from Leiden University Medical Center in Leiden, the Netherlands. "Our study shows that very large data collection of MRI data can lead to improved insight into exactly which brain structures are involved in all sorts of health outcomes, such as obesity."
Obesity represents one of the world's most challenging public health problems. The global pandemic has led to a greater incidence of cardiovascular disease and type 2 diabetes. Previous studies have also tied obesity to an increased risk of accelerated cognitive decline and dementia, suggesting that the disease causes changes to the brain.
To learn more about these changes, the researchers analyzed brain imaging results from more than 12,000 participants in the UK Biobank study, a major trial begun in 2006 to learn more about the genetic and environmental factors that influence disease. The brain scans used sophisticated MRI techniques that provided information on both the neuron-rich gray matter and the white matter, often referred to as the wiring of the brain.
The results show some clear associations in the patients between body fat percentage and brain form and structure, also known as its morphology.
"We found that having higher levels of fat distributed over the body is associated with smaller volumes of important structures of the brain, including gray matter structures that are located in the center of the brain," Dr. Dekkers said. "Interestingly, we observed that these associations are different for men and women, suggesting that gender is an important modifier of the link between fat percentage and the size of specific brain structures."
Analysis showed that, in men, higher total body fat percentage correlated with lower gray matter volume overall and in specific structures involved in the reward circuitry and the movement system. In women, total body fat only showed a significant negative association with the globus pallidus, a structure involved in voluntary movement. For both men and women, higher total body fat percentage increased the likelihood of microscopic changes to the brain's white matter.
The ramifications of these findings, not yet fully clear, could be of significant importance. Smaller gray matter volume suggests loss of neurons, and changes to the white matter could adversely affect the transmission of signals within brain networks. Since the smaller subcortical grey matter volumes are also known to play a role in the food-reward circuitry, these changes may also make it more difficult for obese people to control their weight, Dr. Dekkers said, although more research will be needed to support that connection.
The reason for obesity's adverse effects on the brain are not precisely known. Research has shown that the low-grade inflammation characteristic of obesity can have harmful effects on brain tissue. There is evidence that cellular responses produced in the brain due to inflammation may be behind these effects.
The study looked at overall body fat percentage and did not distinguish between the different types of fat in the body, which Dr. Dekkers said may be an area for additional research. Of particular interest is the visceral white fat found around the abdominal organs. This type of fat, also known as belly fat, is part of metabolic syndrome, a group of factors that increase the risk of cardiovascular disease and diabetes.
"For future research, it would be of great interest whether differences in body fat distribution are related to differences in brain morphological structure, as visceral fat is a known risk factor for metabolic disease and is linked to systemic low-grade inflammation," said the study's senior author, Hildo Lamb, M.D., Ph.D., director of the Cardio Vascular Imaging Group of Leiden University Medical Center.
https://www.sciencedaily.com/releases/2019/04/190423133736.htm