In a two-stage study published in the journal International Psychogeriatrics, Chaoye Guo, of the Shanghai Mental Health Center in China, and colleagues evaluated associations between various MRI markers and cognitive decline in patients with LLD.
First, the authors used data from the Shanghai Action to Prevent the Elderly from Dementia (SHAPE) cohort to compare baseline MRI measures in 40 participants with LLD and stable cognition (LLDcs), 38 participants with LLD and cognitive decline over 2 years (LLDcd), and 47 healthy control participants. Measures included peak width of skeletonized mean diffusivity, global and tract-specific differences in distribution function based on mean diffusivity (DDFMD), gray-matter measures, and regional diffusion tensor image analysis along the perivascular space indices.
Results showed that participants with LLDcd had greater white-matter microstructural burden than both participants with LLDcs and control participants. This burden included higher peak width of skeletonized mean diffusivity, lower global and tract-specific DDFMD, and smaller left nucleus accumbens (L_NAcc) volume.
The authors also evaluated within-group partial correlations between MRI measures and cognitive performance in the LLDcd group. Results showed a link between poorer white-matter integrity and worse performance in orientation and other cognitive domains.
Next, the authors used data from the Sydney Memory and Aging Study sample (21 patients with LLDcs and 16 with LLDcd) to evaluate candidate markers using SHAPE-trained, single-marker Firth logistic models. Results showed that two markers, global DDFMD and L_NAcc volume, retained discrimination of LLDcd after false discovery rate correction.
Overall, the findings suggest that global DDFMD and L_NAcc volume could be used as markers of subsequent decline in patients with LLD. However, the authors note that larger longitudinal studies are needed to validate these markers before they can be used to stratify risk in patients with LLD.