Perceptual priming in Alzheimer's and Parkinson's diseases.

The present study focused on perceptual identification priming (implicit memory) in early stages of dementia by studying demographically and cognitively matched patients with Alzheimer's disease (AD) and Parkinson's disease (PD). The AD and PD groups performed normally on perceptual identification priming, whereas their explicit recognition memory was equally impaired compared to normal controls. These results imply that priming in perceptual identification relies on the perceptual memory system which can resist not only impairments of explicit memory but also widespread cognitive deterioration induced by the neurodegenerative processes in AD or PD.