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

Diabetes treatment may keep dementia, Alzheimer's at bay

Study finds progression of dementia and Alzheimer's signature tangles are much faster in people with untreated diabetes

March 25, 2019

Science Daily/University of Southern California

A new study comparing people with diabetes, prediabetes and normal blood sugar finds that diabetes, left untreated, could mean a higher likelihood of developing dementia, including Alzheimer's disease.

Patients on medication for type 2 diabetes may be keeping Alzheimer's disease away.

USC Dornsife psychologists have found that those patients with untreated diabetes developed signs of Alzheimer's disease 1.6 times faster than people who did not have diabetes.

The study was published March 4 in the journal Diabetes Care.

"Our findings emphasize the importance of catching diabetes or other metabolic diseases in adults as early as you can," says Daniel A. Nation, a psychologist at USC Dornsife College of Letters, Arts and Sciences. "Among people with diabetes, the difference in their rate of developing the signs of dementia and Alzheimer's is clearly tied somehow to whether or not they are on medication for it."

Nation says that this study may be the first to compare the rate of developing the pathology for Alzheimer's disease and dementia among people with normal glucose levels, with pre-diabetes, or people with type 2 diabetes -- both treated and untreated.

For the study, the scientists were comparing the "tau pathology" -- the progression of the brain tangles that are the hallmark of Alzheimer's disease. When the tangles combine with sticky beta-amyloid plaques -- a toxic protein -- they disrupt signals between brain cells, impairing memory and other functions.

Nation and Elissa McIntosh, a USC Dornsife Ph.D. doctoral candidate in psychology, analyzed data collected by the Alzheimer's Disease Neuroimaging Initiative on 1,289 people age 55 and older. Data included biomarkers for diabetes and vascular disease, brain scans and a range of health indicators, including performance on memory tests.

For some participants, Nation and McIntosh were able to analyze 10 years' worth of data, while for others, they had one or four years.

Among 900 of those patients, 54 had type 2 diabetes but were not being treated, while 67 were receiving treatment.

Most people in the study -- 530 -- had normal blood sugar levels while 250 had prediabetes (hyperglycemia).

The researchers compared, among the different diabetic patient categories, the brain and spinal fluid test results that can indicate signs of amyloid plaques and the brain tangles.

"It is possible that the medicines for treating diabetes might make a difference in the progression of brain degeneration," Nation says. "But it's unclear how exactly those medications might slow or prevent the onset of Alzheimer's disease, so that is something we need to investigate."

Increasingly, scientists regard Alzheimer's disease as the result of a cascade of multiple problems, instead of triggered by one or two. The compounding factors range from pollution exposure and genetics (the ApoE4 gene, for instance) to heart disease and metabolic disease.

The study was supported by National Institutes of Health grants R21-AG-055034, P01-AG-052350 and P50-AG-005142 and Alzheimer's Association grant AA-008369.

The Alzheimer's Disease Neuroimaging Initiative is supported by the National Institute on Aging and the National Institute of Biomedical Imaging and Bioengineering, as well as other public and private partners.

https://www.sciencedaily.com/releases/2019/03/190325122011.htm