Fig. 1: Study flowchart of the causal relationships between structural and diffusion IDPs and the risk of major neurodegenerative diseases by using bidirectional TSMR analysis methods.

AD Alzheimer’s disease, ALS amyotrophic lateral sclerosis, CT cortical thickness, FA fractional anisotropy, FTD frontotemporal dementia, GMV gray matter volume, HD Huntington’s disease, IDPs imaging-derived phenotypes, IVW inverse-variance weighted, LBD Lewy body dementia, MD mean diffusivity, ML maximum likelihood, MS multiple sclerosis, PD Parkinson’s disease, RAPS MR-robust adjusted profile scores, SA surface area, TSMR two-sample Mendelian randomization, WM weighted median.