Age and dementia-associated atrophy predominates in the hippocampal head and amygdala in Parkinson's disease

The hippocampus (HC) and amygdala (AG) decrease in volume with age and in Parkinson's disease (PD) with (PDD) and without dementia. We compared 44 PD to 44 age, sex and education-matched subjects without PD (non-PD) and 13 PDD subjects. T1-weighted MR images were used to manually segment the head, body and tail of the HC and the AG. HC volumes, corrected to intracranial volume, were smaller in PDD than non-PD (p = 0.04), reflected predominantly by head atrophy. Right AG volumes were smaller in PD compared to non-PD (p = 0.03). HC volumes in older (>70), but not younger, non-demented PD differed from non-PD (HC, p = 0.02; head, p = 0.03). Age correlated negatively with overall HC (r = −0.43, p = 0.004) and head (r = −0.48, p = 0.001) in PD, but not in non-PD. In PD, left HC head volumes correlated with recall, but not recognition scores on the CVLT-II (r = 0.35, p = 0.02) and BVMT-R (r = 0.35, p = 0.02); AG volumes correlated with CVLT-II recall (r = 0.35, p = 0.02). No correlations were found in non-PD (p > 0.4). In conclusion, functionally meaningful age-associated hippocampal and amygdala atrophy occurs in PD.