Amygdalar and hippocampal MRI volumetric reductions in Parkinson's disease with dementia

Parkinson's disease (PD) involves neuropathological changes in the limbic system that lead to neuronal loss and volumetric reductions of several nuclei. We investigated possible volumetric reductions of the amygdala and hippocampus associated to PD. We carried out magnetic resonance imaging (MRI) volumetric studies in 16 patients with PD and dementia (PDD), 16 patients with PD without dementia (PD), and 16 healthy subjects. The general analysis of variance (ANOVA) showed a significant group effect (for the amygdala, P = 0.01; for the hippocampus, P = 0.005). A post‐hoc test demonstrated that the differences were due to PDD and control group comparisons for the amygdala (P = 0.008) and for the hippocampus (P = 0.004). In nondemented PD subjects, we observed an 11% reduction in the amygdala and a 10% reduction in the hippocampus compared with that in controls. In summary, demented PD patients have clear amygdalar and hippocampal atrophy that remains statistically significant after controlling for global cerebral atrophy. Nondemented PD patients also showed a degree of volumetric reduction in these structures although the differences were not statistically significant. © 2005 Movement Disorder Society