Source memory in normal aging and Parkinson's disease

Several theorists have described memory in Parkinson's disease (PD) as involving an amplification of the deficits seen in normal aging, and drawn parallels between PD and frontal lesion patients. Both normal aging and frontal lobe damage impair memory for the context in which one has encountered information (i.e., source memory). We thus sought to determine whether PD patients would show especially poor source memory. We assessed memory for perceptual (voice), spatial (location of loudspeaker), and temporal (list) source memory in 18 PD patients, 23 healthy older adults, and 35 young people. Although both the healthy aged and PD groups performed more poorly than the young on most of the memory tests, the PD patients failed to show significantly greater impairments than the healthy older adults. The PD patients did perform more poorly, however, on a measure of executive function (the Wisconsin Card Sorting Test [WCST]). We discuss potential reasons why PD had a surprisingly minimal effect on source memory in our study, and relate our data to broader theories of memory impairment in Parkinson's disease.