\begin{table}[htbp]
\centering
\caption{Clinical profile of the subjects in three categories (AD, MCI, NC) categories. Age and MMSE are average values with the standard deviation in parenthesis. MMSE  refers to the Mini-Mental State Exam, a mental cognitive status assessment that evaluates memory, thinking and simple problem-solving abilities, where the maximum (best) score is 30.}

\label{tab:subjects_statistics}
\begin{tabular}{lcccc}
\\
\toprule

    \textbf{Group} & AD & MCI & NC & All   \\
    \midrule
    \textbf{No. of subjects} & 95 & 207 & 104 & 406   \\
    \textbf{Age} & 76.6 (7.1) & 76.0 (7.3) & 77.0 (4.8) & 76.4 (6.7)   \\
    \textbf{Sex (\% M)} & 59.9 & 65.8 & 63.8 & 64.1    \\
    \textbf{MMSE} & 21.1 (4.1) & 26.7 (2.8) & 29.1 (1.2) & 26.1 (2.9)   \\

    
\bottomrule
\end{tabular}
\end{table}