@mtrot
You read this graph more carefully than I did. After I saw the Y axis label "Baseline Corrected Global Composite Cognitive Score (SDU)" I shrugged and gave up looking at it more closely. What does that title mean? What does SDU stand for?
It looks to me like the Y axis is a ratio of some kind with positive and negative values, with zero in the middle. Are these ratios, corrected (normalized) to something? Are differences between ratios of zero and +0.5 to +1.5 large or small? Any thing that compares corrected ratios has a significant error built into it. If you show scores with less correction, without a multiplication or division step in it, these errors will be smaller.