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The 4 Mountains Test: A Short Test of Spatial Memory with High Sensitivity for the Diagnosis of Pre-dementia Alzheimer's Disease
Published on: October 13, 2016
Which memory system is impaired first in Alzheimer's disease?
Mira Didic1, Emmanuel J Barbeau, Olivier Felician
1Service de Neurologie and Neuropsychologie, Pôle de neurosciences cliniques, AP-HM Timone, INSERM U751, Université de la Méditerranée, Marseille, France. mira.didic@ap-hm.fr
Journal of Alzheimer'S Disease : JAD
|July 30, 2011
Summary
Early Alzheimer's disease (AD) may first impair object-based memory due to tau pathology in the anterior subhippocampal region, preceding hippocampal dysfunction and memory loss. This challenges the focus on episodic memory deficits in early AD diagnosis.
Area of Science:
- Neuroscience
- Neuropathology
- Cognitive Psychology
Background:
- Early diagnosis of Alzheimer's disease (AD) is crucial for emerging disease-modifying treatments.
- Current research often focuses on hippocampal dysfunction markers.
- Neurofibrillary tangles (NFTs) in the transentorhinal cortex precede hippocampal involvement in AD.
Purpose of the Study:
- To evaluate the hypothesis that tau deposition in the anterior subhippocampal region leads to context-free memory dysfunction in early AD.
- To propose a model of AD progression based on NFT localization and temporal sequence in the mesial temporal lobe (MTL).
- To challenge the view that episodic memory impairment is the primary early sign of AD.
Main Methods:
- Review of existing findings from animal and human brain-damaged patient studies.
- Evaluation of the proposed hypothesis linking anterior subhippocampal tau deposition to context-free memory deficits.
- Analysis of the temporal sequence of NFT development within the MTL.
Main Results:
- Tau pathology in the anterior subhippocampal region may cause dysfunction in neural networks supporting context-free memory.
- Impaired object-based, context-free memory could be the earliest detectable sign of AD.
- Episodic and spatial memory alterations occur in a later, hippocampal stage of AD.
Conclusions:
- Context-free memory dysfunction, not episodic memory loss, may be the initial behavioral correlate of early AD.
- A revised model of AD progression emphasizes the role of anterior subhippocampal pathology.
- Understanding the sequence of MTL pathology is key to early AD diagnosis and intervention.
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