There is considerable heterogeneity within patients with Parkinson's disease (PD) regarding time from onset of PD to dementia. We compared grey matter atrophy using magnetic resonance images (MRIs) of patients with PD who developed dementia early and late in the disease course. The group with early dementia had more atrophy than the group with late dementia in some areas, while the late dementia group had symmetrical reduction in concentration of grey matter in the insula bilaterally compared to the early dementia group. Our results indicate that the early development of dementia in PD is associated with more severe degeneration of cortical and sub-cortical structures.