Earlier this year, US researchers from Johns Hopkins University, Baltimore, identified biological and anatomical brain alterations associated with Alzheimer’s disease (AD) that occur several decades prior to the onset of clinical symptoms. Findings were published in the journal Frontiers in Aging Neuroscience.
In the published study, researchers analysed data from the BIOCARD study, which aims to identify predictors of cognitive decline among normal individuals who have been followed for almost 20 years. They extracted data from 290 subjects who were cognitively normal when first enrolled and examined nine changepoints in a range of biomarkers during the preclinical phase of AD based on cognitive assessments, cerebrospinal fluid (CSF) values and magnetic resonance imaging (MRI) measures.
Of the 290 participants included at the start of the study, 209 remained cognitively normal at the end of the study period and 81 were diagnosed with mild cognitive impairment or dementia due to AD. All nine measures had significant changepoints, all preceded symptom onset. Scientists detected higher levels of the Tau protein 34 years prior to symptom onset. The levels of a modified version of the Tau protein called "p-Tau" increased 13 years prior to the onset of clinical symptoms. They also found signs of cognitive impairment 11–15 years before the onset of any symptoms. Furthermore, higher levels of Abeta were identified 10 years prior to symptom onset.
https://www.frontiersin.org/articles/10.3389/fnagi.2019.00074/full
