This ZIP-file contains supplementary data belonging to the manuscript "Tracking the brain in myotonic dystrophy: a 5-year longitudinal follow-up study", published in PLOS ONE. In this manuscript we aimed to examine the natural history of brain involvement in adult-onset myotonic dystrophies type 1 and 2 (DM1, DM2). We conducted a longitudinal observational study to examine functional and structural cerebral changes in myotonic dystrophies. We enrolled 16 adult-onset DM1 patients, 16 DM2 patients, and 17 controls. At baseline (T1) and at follow-up (T2) participants underwent neurological, neuropsychological, and 3T-brain MRI examinations using identical study protocols that included voxel-based morphometry and diffusion tensor imaging. The ZIP-file contains imaging result files from the different statistical analyses.