A study concludes that 10% of people over 70 have Alzheimer's, but lack symptoms
A study published in 'Nature' suggests that the prevalence of the disease in old age is higher than estimated
BarcelonaOne in ten people over 70 suffers from dementia due to Alzheimer's disease, but there is also 10% of the population over seventy who suffer from the disease, although they have not yet experienced any symptoms. This is the conclusion of a pioneering study conducted with more than 11,000 blood samples from Norwegian citizens and published this Wednesday in the journal NatureTo assess the prevalence of Alzheimer's disease, an international team of researchers used a database and biological samples from 250,000 Norwegians at the University of Trøndelag (HUNT). From these, they used blood samples from 11,486 people aged 58 and older and analyzed the levels of Tau, the protein responsible for the internal structure of neurons and the proper transmission of molecules. This marker serves as an indicator of amyloid plaques in the brain, a substance that accumulates in large quantities and is considered an unequivocal sign of Alzheimer's. In addition to these analyses, the researchers administered cognitive tests to participants over 70 years of age to compare Tau levels with the presence of dementia. The results of this research showed that approximately 10% of the participants over 70 years of age had Alzheimer's disease and exhibited both symptoms of cognitive decline and elevated Tau levels. Another 10% had elevated Tau levels and showed mild cognitive impairment. Finally, one in ten participants over 70 years of age had high Tau levels but, instead, did not experience symptoms of cognitive decline, a condition known as preclinical Alzheimer's.
A higher proportion than expected
Beyond the proportion of participants who had Alzheimer's without showing symptoms, researchers also observed that, in their study, the proportion of individuals over 85 years old with the neurodegenerative disease was higher than expected. "Our results suggest a higher prevalence of Alzheimer's dementia in older people and a lower prevalence of preclinical Alzheimer's in younger age groups than previously estimated," the researchers stated. In this regard, in the study, 25% of people between 85 and 89 years old presented with dementia and Alzheimer's, a figure much higher than previous estimates, which were approximately 7% for men and 13% for women in this age group in Europe. Conversely, the incidence of preclinical Alzheimer's—that which does not yet show symptoms—in the 70-74 age group was 8%, a proportion lower than the previously estimated 22%.
