Fig. 1. Conditional associations between PSMD (10⁻⁴ mm²/s) and cognitive performance at values of the moderator (mood status).

Individual scatterplots demonstrate significant interaction effects on select cognitive measures. Controls depicted in light green and subjects with LLD depicted in dark green. The relationship between PSMD and slowed processing speed (Trail Making Test, Part A) was magnified among those with LLD. PSMD was associated with poorer performance on measures of cognitive inhibition, semantic fluency, and delayed verbal memory in subjects with LLD, but was unrelated to task performance in these domains in controls. Trail Making Test, Part A and PSMD were log-transformed, all variables were then individually normalized by z-transformation for visualization. Shaded areas surrounding best-fitting lines depict standard errors. PSMD peak width of skeletonized mean diffusivity, LLD late-life depression.