Previous studies using conventional structural measures report varying patterns of grey matter atrophy in patients with early cognitive change in PD30 with several showing no atrophy changes.31 Hippocampal atrophy is reported in cross-sectional studies in PD,32 and is the most consistently abnormal region in longitudinal structural MRI.33 Thalamic changes are also linked with cognition in PD.30 However, a significant relationship between MoCA and grey matter volume has not been shown in PD.34 This evidence concerns the gene DOCK3 and hippocampal atrophy.