Fig. 1.

Figure reprinted with permission: Sterling NW, Wang M, Zhang L, et al. Stage-dependent loss of cortical gyrification as Parkinson disease “unfolds”. Neurology 2016; 86(12):1143–1151. Comparison of local gyrification index between Parkinson disease (PD) subgroups and controls (left) and among PD subgroups (right) at baseline. In this study PD patients were grouped based on the number of years since diagnosis into PD-early (< 1 year, baseline UPDRS-III on medication of 11.4 ± 8.2, baseline Hoehn and Yahr stage 1.4 ± 0.6), PD-middle (1–5 years, baseline UPDRS-III on medication of 19.8 ± 10.4, baseline Hoehn and Yahr stage 1.4 ± 0.6), and PD-late (> 5 years, baseline UPDRS-III on medication of 20.4 ± 11.9, baseline Hoehn and Yahr stage 2.2 ± 0.6). PD with a long disease duration demonstrated significantly reduced gyrification bilaterally in the inferior parietal, precentral and postcentral, and superior frontal areas, compared to controls at baseline visit (left). These patients also had reduced gyrification in several neocortical areas, compared to PD with short and medium disease duration at baseline (right).