Box plots and superimposed data points showing the distribution of Alzheimer disease (AD) biomarkers by baseline diagnosis and visit. The horizontal line in each box indicates the median, whereas the top and bottom borders of the box mark the 75th and 25th percentiles, respectively. The whiskers above and below the box mark the largest and smallest data point that is within 1.5 times the interquartile range of the top and bottom of the box. A, For participants with both baseline and 12-month data, the cerebrospinal fluid (CSF) Aβ42 level did not change from baseline to 12 months in the cognitively normal (CN) group (P = .52), the mild cognitive impairment (MCI) group (P = .13), or the AD group (P = .51). B, The CSF total tau level is shown on the log scale. It increased from baseline to 12 months in CN participants (P = .002) but not in participants with MCI (P = .12) or AD (P = .36). The dotted horizontal line extending across all box plots represents the cut point denoting normal vs abnormal for each biomarker.