Assessment of verbal and visuospatial working memory in mild cognitive impairment and Alzheimer's dementia.

Roy P.C. Kessels,Anouk Overbeek,Zita Bouman

doi:10.1590/1980-57642015dn93000014

Roy P.C. Kessels, Anouk Overbeek + Show 1 more

Open Access

https://doi.org/10.1590/1980-57642015dn93000014

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Journal: Dementia & Neuropsychologia	Publication Date: Sep 1, 2015
Citations: 28	License type: cc-by

Affiliation: Radboud University Nijmegen

Abstract

In addition to episodic memory impairment, working memory may also be compromised in mild cognitive impairment (MCI) or Alzheimer's dementia (AD), but standard verbal and visuospatial span tasks do not always detect impairments.ObjectiveTo examine whether more complex verbal and visuospatial working memory tasks result in more reliable impairment detection.MethodsThe Digit Span (forward, backward and sequencing), Spatial Span (forward and backward) and Spatial Addition test from the Wechsler batteries were administered to MCI and AD patients and performance compared to healthy older adult controls.ResultsResults showed that both the MCI and AD patients had impaired performance on the Spatial Addition test. Both groups also had impaired performance on all three Digit Span conditions, but no differences were found between forward and backward conditions in any of the groups. The sequencing condition differed from the backward condition only in the AD group. Spatial Span performance was impaired in AD group patients but not in MCI patients.ConclusionWorking memory deficits are evident in MCI and AD even on standard neuropsychological tests. However, available tests may not detect subtle impairments, especially in MCI. Novel paradigms tapping the episodic buffer component of working memory may be useful in the assessment of working memory deficits, but such instruments are not yet available for clinical assessment.

Highlights

Alzheimer’s disease patients typically present with profound long-term memory deficits
Long-term memory function has been extensively studied in mild cognitive impairment (MCI) and Alzheimer dementia (AD), yet less attention has been paid to working memory
Dunnett post-hoc comparisons showed that the MCI group performed worse than the healthy controls on Digit Span forward, backward and sequencing (p=0.029, p=0.02, p=0.026, respectively) as well as on Spatial Addition (p

Summary

Introduction

Alzheimer’s disease patients typically present with profound long-term memory deficits. These impairments are already evident in the pre-dementia stage of the disease, referred to as Mild Cognitive Impairment,[1] and become more profound in the Alzheimer dementia (AD) stage, in which everyday functioning is affected. The model consists of two slave systems: the phonological loop for verbal information and the visuospatial sketchpad for visual and spatial information.[2] The capacity of the phonological loop is typically assessed using digit span tasks, while the visuospatial sketchpad can be assessed using spatial span tests.[3] Both working memory components function under the control of the Central Executive (CE) which is recruited under higher memory loads. Backward span taps the CE to a greater extent than forward span

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