Implicit and explicit memory in patients with Parkinson's disease with and without dementia.
OBJECTIVE
To study explicit and implicit memory processes in patients with Parkinson's disease.


METHODS
Case-control design. All subjects were given a neuropsychological test battery, and the test scores were compared among the groups.


METHODS
Government-funded research facility. All subjects were examined as outpatients.


METHODS
We tested nondemented (n = 13) and demented (n = 5) patients with Parkinson's disease and normal controls (n = 12) matched for age, gender, and educational level.


METHODS
Memory for verbal and pictorial stimuli under both explicit and implicit retrieval conditions.


RESULTS
Both nondemented and demented patients with Parkinson's disease exhibited impairment on tests of explicit memory. Their impairment could be graded based on the level of effort required by the task: impaired free recall in nondemented patients and impaired free recall, cued recall, and recognition in demented patients. By contrast, neither group showed evidence of impairment on automatic (modality monitoring and word frequency estimation) or implicit (word and picture fragment identification) memory tasks. Correlation analyses did not support any association between the effortful memory deficits and neurologic variables, mood, or performance on executive function tests.


CONCLUSIONS
Memory deficits in patients with Parkinson's disease primarily involve the conscious, effortful strategic aspects of searching long-term memory.
Appollonio
I
I
Cognitive Neuroscience Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Md.
Grafman
J
J
Clark
K
K
Nichelli
P
P
Zeffiro
T
T
Hallett
M
M
D000368:Aged; D000704:Analysis of Variance; D003463:Cues; D003704:Dementia / Q000150:complications / Q000503:physiopathology / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000503:physiopathology / Q000523:psychology*