deletions | additions       diff --git a/sec_Biomarkers_of_AD.tex b/sec_Biomarkers_of_AD.tex  index 01c0265..a7e5c67 100644  --- a/sec_Biomarkers_of_AD.tex  +++ b/sec_Biomarkers_of_AD.tex 
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These biomarkers have different relevance at different stages of AD progression.  Jack et al \cite{Jack2010,Jack_2013} describe the temporal evolution of AD biomarkers and their interrelationships amongst themselves, and with the onset and progression of clinical symptoms.  Figure \ref{fig:hypotheticalModelJack_2013} shows the staging of the disease and the biomarkers of AD as proposed by by Jack et al in \cite{Jack2010,Jack_2013}.  Currently there are five Well  established biomarkers for AD: AD till date are the following:  \begin{itemize}  \item Cerbrospinal fluid (CSF) based and imaging based biomarkers targeting  A$\beta$ protein pathology  \item Tau protein CSF based and imaging based biomarkers (very recent and still under research) targeting taupathy  \item FDG PET Flurodeoxyglucose based positron emission tomography (FGD-PET) targeting neurodegeneration  \item Structural magnetic resonance imaging (MRI) based morphometry targeting neurodegeneration and tissue  atrophy \item cognitive Cognitive  impairment \end{itemize}  Cognitive impairment starts to appear years after the changes in the other biomarkers.  In the following sections we consider the remainingfour  biomarkers individually.