Scientists of the Johns Hopkins University, in Baltimore (United States), have detected biological and anatomical brain changes related to Alzheimer's disease that occur between 3 to 10 years before the first recognizable symptoms of the disease appear, although some appear some even more than 30 years before.
MADRID. "Our study suggests that it is possible to use brain imaging and cerebrospinal fluid analysis to assess the risk of Alzheimer's disease at least 10 years or more before the most common symptoms occur, such as mild cognitive impairment," explains Laurent Younes, professor and president of the Department of Applied Mathematics and Statistics at Johns Hopkins University.
Younes warns that brain changes vary widely in people and that the results of their research reflect an average level of such changes in a small group of research subjects, so for now can not be used to draw precise conclusions about the brain changes in individuals since there is no drug or other known intervention to slow or stop the disease process, even if the risk is identified early. But the work, he adds, could be used to develop a test to determine an individual's relative risk of contracting Alzheimer's disease and guide the use of treatments when they develop.
For the study, published in 'Frontiers in Aging Neuroscience', the scientists reviewed the medical records compiled from 290 people over 40 years old by the National Institutes of Health and the School of Medicine at Johns Hopkins University as part of the BIOCARD project, in an effort to develop predictors of cognitive decline led by Johns Hopkins neurologist, Marilyn Albert. Most of the 290 people had at least one first-degree relative with dementia of the Alzheimer's type, which puts them at a higher than normal risk.
As part of the BIOCARD studies, the scientists collected cerebrospinal fluid and performed MRI brain scans of the study participants every two years between 1995 and 2005. They also performed five standard tests of memory, learning, reading and care annually from 1995 to 2013
Because the 290 participants were cognitively normal when the study began, the scientists were able to trace several biological and clinical characteristics associated with Alzheimer's disease in the years prior to the onset of symptoms. At the time of their last appointment with the BIOCARD project, 209 study participants remained cognitively normal and 81 were diagnosed with mild cognitive impairment or dementia due to Alzheimer's disease.
In the 81 people who developed cognitive problems or dementia, the Johns Hopkins team found subtle changes in cognitive test scores from 11 to 15 years before the onset of clear cognitive decline. They also found increases in the rate of change of a protein called Tau, which has long been considered a marker of Alzheimer's disease, in the cerebrospinal fluid an average of 34.4 years (for t-tau, or total Tau) and 13 years (for one year). modified version called p-tau) before the onset of cognitive decline.