Are perception and memory for faces influenced by a specific age at onset factor in Parkinson's disease?

This study investigated the possibility that a specific age at onset factor in Parkinson's disease results in qualitative differences in cognitive functioning between early- and late-onset patients without dementia. Both early- and late-onset patients performed more poorly than matched controls on face-matching, recognition memory for unfamiliar faces and famous face identification. When the performance of the early- and late-onset patients was contrasted, alongside that of controls, both Parkinson's disease and age were found to be factors that influenced cognitive ability. No interaction between these factors emerged. These results suggest that performance of early- and late-onset Parkinson's disease patients without dementia may be quantitatively different and lend no further support to the proposal that two separate disorders exist.