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

This study has been completed.
Sponsor:
Information provided by:
National Institutes of Health Clinical Center (CC)
ClinicalTrials.gov Identifier:
NCT00004557
First received: February 8, 2000
Last updated: March 3, 2008
Last verified: February 1999
  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.


Condition
Dementia

Study Type: Observational
Official Title: Models of Disordered Knowledge and Memory Systems in Dementia and Related Disorders

Resource links provided by NLM:


Further study details as provided by National Institutes of Health Clinical Center (CC):

Estimated Enrollment: 650
Study Start Date: January 1992
Estimated Study Completion Date: April 2000
Detailed Description:

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.

  Eligibility

Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
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.

  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00004557

Locations
United States, Maryland
National Institute of Mental Health (NIMH)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
  More Information

Publications:
ClinicalTrials.gov Identifier: NCT00004557     History of Changes
Other Study ID Numbers: 920075, 92-M-0075
Study First Received: February 8, 2000
Last Updated: March 3, 2008
Health Authority: United States: Federal Government

Keywords provided by National Institutes of Health Clinical Center (CC):
Attention
Cognition
Dementia
Memory
Object Recognition
Spatial Processes

Additional relevant MeSH terms:
Dementia
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases
Delirium, Dementia, Amnestic, Cognitive Disorders
Mental Disorders

ClinicalTrials.gov processed this record on September 18, 2014