The leading risk factor for Alzheimer Disease in the United States appears to have shifted over the past decade.
Back in 2011the most prominent modifiable risk factor for Alzheimer’s disease was physical inactivity, followed by depression and smoking.
However, according to a current cross-sectional analysis, lack of exercise now ranks second after obesity when it comes to the development of dementia.
Today, Alzheimer’s disease is the most common form of dementia and one of the leading causes of death in the United States. However, despite much research, no one knows how the disease begins or how to stop its progression.
Research suggests there is a strong genetic component at play, but numerous environmental factors are also coming to light that may contribute to the disease, including poor diet, high blood pressure, depression, smoking and more gingivitis.
The good news is that these factors can be controlled by patients and doctors to reduce the risk of disease. The bad news is that the impact of these risk factors is constantly changing, year after year, from country to country.
Why this is so remains unclear, but it could be due to a combination of changing public health concerns and improving research methods.
For example, in the most recent analysis from the USA, hearing loss was added as a risk factor for Alzheimer’s that can be influenced, although it has not previously been taken into account in estimates.
In addition, the rate of midlife obesity in the United States has more than doubled since 2010. The prevalence of physical inactivity and smoking has declined somewhat in recent years.
In light of these important changes, researchers performed an updated risk assessment for Alzheimer’s disease using data from the 2018 US Behavioral Risk Factor Surveillance Survey.
Of the 378,615 people included, just over a third of all Alzheimer’s cases were associated with one of the eight risk factors. These risk factors have been self-reported, meaning they’re not perfect measurements, but they do indicate a general trend.
The most common risk factor identified in the nationwide analysis was midlife obesity, followed by physical inactivity and low educational attainment.
“Above all,” according to the author of the latest estimate writes“The change in the prevalence of midlife obesity appears to be the largest compared to other factors assessed in this study, which may have led to midlife obesity becoming the most important risk factor [Alzheimer disease and related dementias] Almost a decade later.”
This is not the first time that midlife obesity has been linked to the onset of Alzheimer’s.
A to learn found evidence that excess body weight could make nerve tissue more susceptible to brain damage or cell loss. These changes also appear to occur in parts of the brain closely related to memories.
That doesn’t mean midlife obesity is a direct cause of Alzheimer’s, but it does suggest that maintaining a healthy weight can reduce your chances of developing the disease — at least to some extent.
Similar studies have also shown that when Weight is lost later in lifethe cerebral cortex is not thinned nearly as much as with obesity.
There is a bunch of hypotheses Why it is like that. Some researchers suggest that obesity can impair blood flow in the brain, leading to a lack of oxygen in some areas.
Other researchers suspect that obesity can lead to chronic inflammation in the brain, which can break down white matter and impair neural connections.
Finding out who in the population is most susceptible to Alzheimer’s could one day help scientists refine future research and provide doctors with better treatment options.
For example, in the 2018 analysis, when the researchers split survey participants by gender, race, and ethnicity, they found some key differences in the data.
Cases of Alzheimer’s associated with at least one of the eight modifiable risk factors were more common in men than in women. They were also more common among older Blacks, American Indians and Alaska Natives, and Hispanics compared to Whites.
The results suggest that some groups of people are at greater risk of developing Alzheimer’s than others, possibly because of socioeconomic, cultural, or environmental factors that limit access to health care, physical activity, or healthy, affordable food.
Culture certainly seems to play a strong role. Aside from Australia and Latin America, the US is one of the few countries where midlife obesity is a leading risk factor for Alzheimer’s.
In China and Europe, low education and physical inactivity are the two most important risk factors. Obesity does not rank in the top three.
The authors of the US analysis argue that policymakers and clinicians should increase their efforts to prevent Alzheimer’s disease by focusing not only on midlife obesity but also on physical inactivity and low education, particularly among high-risk groups.
A different strategy may be required in other parts of the world.
Alzheimer’s is not a simple disease and the way we approach it will undoubtedly involve great complexity.
The study was published in JAMA.
