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The nature and staging of attentional dysfunction in early (mininal and mild) Alzheimer's disease: Relationship to episodic and semantic memory impairment.
Perry, R.J., WATSON, P., HODGES, J.R.
Neuropsychologia, (2000), 38, 252-271.
Year of publication:
The development of cholinergic therapies for Alzheimer's disease (AD) has highlighted the importance of understanding the role of attentional deficits and the relationship between attention and memory in the earliest stages of the disease. Variability in the tasks used to examine aspects of attention, and in the disease severity, between studies makes difficult to determine which aspects of attention are affected earliest in AD, and how attentional impairment is related to other cognitive modules. We tested 27 patients in the early stages of the disease on the basis of the MMSE on a battery of attentional tests. Although the mildly demented group were impaired on all attentional tests, the minimally impaired group showed a preserved ability to sustain attention, and to divide attention based on a dual-task paradigm. The minimally demented group had particular problems with response inhibition and speed of attentional switching. Examination of the relationship between attention and other cognitive domains showed impaired episodic memory in all patients. Deficits in attention were more prevalent than deficits in semantic memory suggesting that they occur at an earlier stage and the two were partially independent. Impairment in visuoperceptual and visuospatial functions and verbal short-term memory were the least common. Although attention is impaired early in AD, 40% of our patients showed deficits in episodic memory alone, confirming that amnesia may be the only cognitive deficit in the earliest stages of sporadic AD.