The pattern of cortical atrophy in Parkinson's disease with mild cognitive impairment according to the timing of cognitive dysfunction.

The density of Lewy bodies or the concurrent β-amyloid pathology would act as modulators in the relative timing of dementia during the course of Parkinson's disease. Depending on the temporal relationship between the onset of parkinsonism and that of cognitive impairment, patients with Parkinson's disease with mild cognitive impairment were divided into two groups of earlier (<1 year) and later (≥1 year) cognitive decline, and cortical atrophy patterns and correlation of gray matter and timing of cognitive decline were analyzed using voxel-based morphometry. The morphometric analysis showed that patients with earlier cognitive decline demonstrated greater cortical atrophy in the inferior parietal and orbitofrontal areas than did those with later cognitive decline. Additionally, the anatomical bases of the timing of their cognitive decline differed in terms of correlation patterns. These data suggest that the pathological burden in Parkinson's disease with mild cognitive impairment may be more severe in patients with earlier cognitive decline than in those with later cognitive decline, and that the neural basis corresponding to the timing of cognitive decline may differ in these patients.