Dissociations in visual attention deficits among persons with mild cognitive impairment

Impairments in visual attention and visual information processing have been identified as part of the neuropsychological features of Alzheimer's disease (AD), even in its earliest stages. There is increasing recognition that these deficits may be selective rather than global, with some attentional subtypes being more vulnerable than others. The few studies that have investigated attentional deficits in mild cognitive impairment (MCI), a putatively prodromal phase of AD, have not satisfactorily addressed the possible selectivity in attentional deficits in MCI. This study examined potential dissociations in visual attention deficits in MCI using a measure that assesses simple, divided, and selective attention. The results indicated a hierarchy of attentional impairments, with divided attention being the most affected and simple attention the least. Among participants with MCI, 53% showed evidence of impairment in divided attention compared to 19% of controls (OR = 4.81, p < .001). Poorer visual attention was also associated with poorer overall cognitive status. The implications of these findings for early identification of MCI, prevention of functional decline in MCI, and delay/reversal of cognitive degradation in MCI are discussed.