Assessment of working-memory deficits in patients with mild cognitive impairment and Alzheimer’s dementia using Wechsler’s Working Memory Index

Abstract

Although episodic memory deficits are a hallmark in mild cognitive impairment (MCI) and Alzheimer's dementia (AD), little attention has been paid so far to the ability to maintain and manipulate information during a brief period of time, i.e. working memory. In this study, we examine verbal working memory in both cognitively unimpaired older people and MCI and AD patients. Seventy- five participants were examined with either no cognitive impairment (n=25), MCI (n=25) or AD (n=25). Working memory was investigated with Wechsler's Working Memory Index tests (Digit Span, Letter-Number Sequencing and Arithmetic). Both MCI and AD patients performed worse on all three working-memory tests compared with controls, the subtest Letter-Number Sequencing also revealing worse performance in AD compared with MCI patients. Workingmemory deficits are already present in MCI patients and worsen in AD patients, suggesting that working memory should be assessed as part of neuropsychological testing.