Longitudinal evaluation of cerebral morphological changes in Parkinson's disease with and without dementia.

Objective: To investigate the pattern of brain atrophy across time in a sample of Parkinson's disease (PD) patients with and without dementia using voxelbased morphometry (VBM) analysis.

Methods: The initial sample comprised thirteen non-demented PD patients and sixteen demented patients. Longitudinal cognitive assessment and structural MRI were performed. The mean follow-up period was 25 months (SD=5.2). From this initial group, eight PD patients with dementia (5 men and 3 women) and eleven PD patients without dementia (7 men and 4 women) were reevaluated. MRI 3D structural images were acquired and analyzed by means of the optimized VBM procedure with Statistical Parametric Mapping (SPM2).

Results: VBM analysis showed a progressive grey matter volume decrease in patients with PD without dementia in limbic, paralimbic and neocortical associative temporooccipital regions. In patients with dementia the loss mainly involved neocortical regions.

Conclusion: VBM revealed a significant loss of grey matter volume in PD patients with and without dementia with disease progression. The decrease in limbic and paralimbic regions is widespread in non-demented patients. Neocortical volume reduction is the most relevant finding in patients with dementia. This suggests that the neocortex is a substrate for dementia in Parkinson disease.