Implicit and explicit memory in Alzheimer's disease and Parkinson's disease

Abstract

Several tasks examined implicit and explicit memory in matched samples of Alzheimer's (AD) and Parkinson's disease (PD) patients, and healthy elderly subjects. Lexical priming, pursuit-rotor tracking, and a fragmented pictures test, followed by explicit memory tests, were given. AD patients were impaired on all explicit tests and on lexical priming, but were intact on pursuit-rotor tracking and the procedural learning (PL) component of the fragmented pictures test. PD patients were significantly better than AD patients on all explicit memory tests, but were selectively impaired on the PL component of the fragmented pictures test. Finally, a mirror reading test was given to the PD patients and matched control subjects, with no significant differences in performance between the two groups demonstrated. Results are discussed in terms of hypothetical cognitive processes and brain circuits underlying different explicit and implicit memory domains.