Expired Study
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Bethesda, Maryland 20892


Purpose:

Patients with Alzheimer's disease (AD) perform poorly on tasks dependent on access to, and utilization of, previously acquired knowledge and skills. It has been commonly assumed that impaired knowledge in AD, as well as in other patients with cortical lesions, is due to an actual loss or disorganization of a specific knowledge base or system. This hypothesis has, however, recently been called into question by data from tasks that purport to tap knowledge on a more automatic and implicit level. For example, although AD patients are impaired on object naming and verbal fluency tasks, they show a normal pattern of semantic facilitation on reaction time based priming tasks. In fact, the level of facilitation or activation on these tasks has often been reported to be greater in AD patients than in normal individuals. These and similar data have been used to support arguments that performance decrements in AD patients are due to deficits in attentional and/or retrieval processes rather than a degradation of knowledge stores. The central focus of this project will be to test a model of the semantic representations of object that predicts increased facilitation or hyperpriming in AD patients as a result of degraded representations. The relationship between performance on on-line priming tasks, visual attention and spatial processes, and explicit and implicit measures of memory also will be examined. In addition to normal controls, patients with cognitive and memory impairments, but without semantically-based naming difficulties (elderly depressed, Huntington's disease, Korsakoff's disease) will serve as controls for overall slowness of response and degree of explicit memory deficit.


Study summary:

Patients with Alzheimer's disease (AD) perform poorly on tasks dependent on access to, and utilization of, previously acquired knowledge and skills. It has been commonly assumed that impaired knowledge in AD, as well as in other patients with cortical lesions, is due to an actual loss or disorganization of a specific knowledge base or system. This hypothesis has, however, recently been called into question by data from tasks that purport to tap knowledge on a more automatic and implicit level. For example, although AD patients are impaired on object naming and verbal fluency tasks, they show a normal pattern of semantic facilitation on reaction time based priming tasks. In fact, the level of facilitation or activation on these tasks has often been reported to be greater in AD patients than in normal individuals. These and similar data have been used to support arguments that performance decrements in AD patients are due to deficits in attentional and/or retrieval processes rather than a degradation of knowledge stores. The central focus of this project will be to test a model of the semantic representations of object that predicts increased facilitation or hyperpriming in AD patients as a result of degraded representations. The relationship between performance on on-line priming tasks, visual attention and spatial processes, and explicit and implicit measures of memory also will be examined. In addition to normal controls, patients with cognitive and memory impairments, but without semantically-based naming difficulties (elderly depressed, Huntington's disease, Korsakoff's disease) will serve as controls for overall slowness of response and degree of explicit memory deficit.


Criteria:

Subjects will include: Patients assigned a diagnosis of probable Alzheimer's disease meeting NINCDS-ADRDA and DSM-III-R criteria. Patients with other neuropsychiatric illness (i.e., depression, Korsakoff's disease, Huntington's disease). Normal controls. Subjects must not have major concomitant illness. All patients will be drug-free for at least 2 weeks whenever possible. Concurrent use of some medications (i.e., diuretics or antibiotics) will be allowed only after careful review by the investigators. Normal control subjects will be without a history of or present psychiatric or neurological illness.


Study is Available At:


Original ID:

920075


NCT ID:

NCT00004557


Secondary ID:

92-M-0075


Study Acronym:


Brief Title:

Models of Disordered Knowledge and Memory Systems in Dementia and Related Disorders


Official Title:

Models of Disordered Knowledge and Memory Systems in Dementia and Related Disorders


Overall Status:

Completed


Study Phase:

N/A


Genders:

Both


Minimum Age:

N/A


Maximum Age:

N/A


Quick Facts

Healthy Volunteers
Oversight Has DMC
Study Is FDA Regulated
Study Is Section 801
Has Expanded Access

Study Source:

National Institutes of Health Clinical Center (CC)


Oversight Authority:

United States: Federal Government


Reasons Why Stopped:


Study Type:

Observational


Study Design:

N/A


Number of Arms:

0


Number of Groups:

0


Total Enrollment:

650


Enrollment Type:


Study Dates

Start Date:January 1992
Completion Date:April 2000
Verification Date:February 1999
Last Changed Date:March 3, 2008
First Received Date:February 8, 2000

Study Outcomes

There are no available Study Outcomes

Study Interventions

There are no available Study Interventions

Study Arms

There are no available Study Arms

Study Agencies

Agency Class:NIH
Agency Type:Lead Sponsor
Agency Name:National Institute of Mental Health (NIMH)

Sample and Retention Information

There are no available Sample and Retention Information

Study References

Reference Type:Reference
Citation:Balota DA, Duchek JM. Semantic priming effects, lexical repetition effects, and contextual disambiguation effects in healthy aged individuals and individuals with senile dementia of the Alzheimer type. Brain Lang. 1991 Feb;40(2):181-201.
PMID:2036582
Reference Type:Reference
Citation:Bayles KA, Tomoeda CK. Confrontation naming impairment in dementia. Brain Lang. 1983 May;19(1):98-114.
PMID:6222782
Reference Type:Reference
Citation:Butters N, Granholm E, Salmon DP, Grant I, Wolfe J. Episodic and semantic memory: a comparison of amnesic and demented patients. J Clin Exp Neuropsychol. 1987 Oct;9(5):479-97.
PMID:2959682

Data Source: ClinicalTrials.gov

Date Processed: November 18, 2019

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