About 50 million Americans may be in the early stages that lead to Alzheimer's disease at this time, according to a new prognosis.
And 6 million people probably have it now, the team at the University of California in Los Angeles estimated.
The prognosis is based on a large number of assumptions, as well as on some hard data, but it is the best estimate of the severity of Alzheimer's disease in the country in the coming years, said Keith Fargo, of the Association of Alzheimer, who did not participate in the investigation.
"As far as we know, this is the first time anyone does This kind of estimate, "said Fargo, director of scientific programs and outreach at the Alzheimer's Association.
For the unusual study, Ron Brookmeyer, a biostatistician at the University of California, Los Angeles and his colleagues collected all the data they could find from studies of Alzheimer's disease.
To calculate who was at risk for developing Alzheimer's, they used measures that included the accumulation of a protein in the brain called amyloid, the loss of brain cells and the loss of memory and skills, such as reading and writing.
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They used other studies that included a look at 1,500 volunteers living at the Mayo Clinic in Minnesota, which included healthy people who are not at risk Particular of Alzheimer's. They used studies of people with mild cognitive impairment (memory loss that can lead to Alzheimer's) and people diagnosed with Alzheimer's dementia.
And they saw actual reports of people who have Alzheimer's disease now.
They then made calculations to predict how many people would probably progress to Alzheimer's disease at this time, although they may not know it.
"It's practically all extrapolation." He is analyzing real cohorts based on the community that have been studies, "said Fargo.
"But it's not about systematically passing through the population, it's a model-based estimate."
But it uses solid data and methods that should at least be a start to predicting the future cost of Alzheimer's, Fargo said.
"For the first time, scientists have attempted to account for the number of people with biomarkers or other evidence of possible preclinical Alzheimer's disease, but who have no Alzheimer's disease or dementia," the National Institutes of Health, who helped pay for the study, he said in a statement.
"People with such signs of preclinical disease are at higher risk of developing Alzheimer's dementia."
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"It is estimated that 46.7 million American adults over the age of 30 are in this hypothetical preclinical stage of Alzheimer's disease and another 2.43 million have mild cognitive impairment due to Alzheimer's disease, although many do not they will progress to dementia during their lifetime, "Brookmeyer and colleagues wrote
" In 2017, there were 3.65 million cases of clinical Alzheimer's in the United States, "they wrote in their report, published in the journal Alzheimer & # 39; s & Dementia: The Journal of the Alzheimer & # 39; s Association.
"We estimate that approximately 1.54 million (42 percent) of the 3.65 million cases living today have advanced clinical Alzheimer's disease that requires a level of care equivalent to nursing homes," they added.
"We anticipate that by 2060, the prevalence in the US of clinical Alzheimer's disease will grow to 9.3 million."
By the year 2060, they predict, more than 75 million people will have preclinical Alzheimer's disease, which means that the disease is developing their brains, but it has not caused enough symptoms to be diagnosed.
Alzheimer's disease is the most common form of dementia. There is no cure for that and there is no good treatment.
So, why try to calculate the extent of an incurable disease?
"There are things you can do," said Fargo. "These are the numbers of people with whom we could potentially intervene"
Although there is no good treatment now, several studies have shown that Alzheimer's can be prevented in some people with a better diet, more exercise and other healthy habits.
And the hope is to develop drugs that can prevent Alzheimer's, just like statins and blood pressure lowering drugs prevent strokes and heart attacks now.
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In addition, not all people with brain damage associated with Alzheimer's develop the disease. "There is a group of people who have changes in the brain but never experience symptoms of dementia," the Alzheimer's Association said in a statement.
"It should not be scary, it should be seen as an indicator of the future in which we have a window of opportunity for prevention, just as we do today with cholesterol and heart disease," said Fargo.
"Even if this estimate turns out to be true, that does not mean that those 46 million people will develop dementia because of Alzheimer's disease," Fargo added.
"Just as you can have high cholesterol today and not develop a heart disease, heart attack or stroke, you may be in this preclinical state but not develop later the dementia of Alzheimer's disease."