Biomarkers of Alzheimer's disease

Abstract

Although a battery of neuropsychological tests are often used in making a clinical diagnosis of Alzheimer's disease (AD), definitive diagnosis still relies on pathological evaluation at autopsy. The identification of AD biomarkers may allow for a less invasive and more accurate diagnosis as well as serve as a predictor of future disease progression and treatment response. Importantly, biomarkers may also allow for the identification of individuals who are already developing the underlying pathology of AD such as plaques and tangles yet who are not yet demented, i.e. "preclinical" AD. Attempts to identify biomarkers have included fluid and imaging studies, with a number of candidate markers showing significant potential. More recently, better reagent availability and novel methods of assessment have further spurred the search for biomarkers of AD. This review will discuss promising fluid and imaging markers to date.

On the early diagnosis of Alzheimer's Disease from multimodal signals: A survey

“…The ratio of tau-epitopes to Aˇ42, in agreement with the precedent results, have also been found to be predictors of AD in MCI patients [67]. Other chemical components like CSF Isoprostanes which have been found to be increased in AD patients even in the preclinical stage [68] and ˛1-antichymotrypsin, Interleukin-6 and various markers of inflammation which have given ambiguous results [60], even if much less frequently, are also present in the literature. Recently, it has been concluded that the amount of CSF in the hippocampal region is also related to AD [69].…”

“…In the recent years, some researches have focused on identifying reliable and valid biomarkers of AD in biofluids [60]. One of these biofluids is the CSF, which is a clear fluid that surrounds the brain and spinal cord mainly for protection.…”

“…Aˇ40 is also present in the literature but no significant differences have been found for AD patients [63], and sometimes ratios between both Aˇ species have also been computed, suggesting that it has potential for both for distinguishing AD patients from healthy subjects and to predict AD in people suffering from MCI [60,[63][64][65]. CSF total tau, as well as some specific tau epitopes (p-tau231, p-tau181 and p-tau199), have been found to increase in AD [34,66] and some researches also affirm its predictability from MCI to AD [60,67]. The ratio of tau-epitopes to Aˇ42, in agreement with the precedent results, have also been found to be predictors of AD in MCI patients [67].…”

Evaluación de la enfermedad de Alzheimer en etapa temprana: biomarcadores y pruebas neuropsicológicas

“…Altas concentraciones de t-tau junto a bajas concentraciones de Aβ 42 pueden detectar la EA con alta sensibilidad y especificidad 46 . Lo mismo ocurre para altas proporciones en concentración de f-tau/Aβ 42 47 , teniendo más potencial como biomarcador de diagnóstico que de progresión 48 .…”

The Role of Physical Fitness in the Neurocognitive Performance of Task Switching in Older Persons with Mild Cognitive Impairment

“…Although some well-characterized biomarkers (e.g., tau protein and amyloid-␤42 in cerebrospinal fluid) and sophisticated neuroimaging instruments [e.g., magnetic resonance imaging (MRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET)] have been shown to reliably detect early AD pathology [17], there are still some significant limitations to these approaches, such as low to moderate sensitivity and specificity of preclinical measurements, high costs, invasiveness, need of radioactive tracers, and the absence of standardization and clear diagnostic cutoff values [17][18][19]. Several reports over the past decade described the potential diagnostic importance of electrophysiological markers of cognitive decline in patients with MCI and the preclinical stage of AD, as obtained by analysis of the electroencephalography-derived event-related potentials (ERPs) [20][21][22][23][24][25][26][27][28][29].…”