Journal Article

The functional anatomy of divided attention in amnestic mild cognitive impairment

Thomas M. Dannhauser, Zuzana Walker, Tim Stevens, Lean Lee, Marc Seal and Sukhwinder S. Shergill

in Brain

Published on behalf of The Guarantors of Brain

Volume 128, issue 6, pages 1418-1427
Published in print June 2005 | ISSN: 0006-8950
Published online February 2005 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awh413
The functional anatomy of divided attention in amnestic mild cognitive impairment

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Recent neuroimaging studies have demonstrated changes in brain function in cognitively normal subjects at increased risk of developing Alzheimer's disease. Amnestic mild cognitive impairment (AMCI) carries a high risk of developing into Alzheimer's disease. In AMCI altered cortical activation has been demonstrated during memory tasks, using functional MRI (fMRI). Memory and attention are closely related cognitive functions. It is unclear whether the memory impairment of AMCI is associated with attentional deficits of the sort likely to be revealed by tasks requiring divided attention. Ten older adults (mean age 72 years, range 57–81 years) with AMCI were compared with healthy matched controls on divided attention and passive sensory processing tasks using fMRI. During the divided attention task both groups activated similar regions of left hemispheric prefrontal and extrastriate visual cortex. However, the AMCI group had attenuated prefrontal activation compared with age matched controls. On the passive sensory processing task there was no difference between the AMCI and control groups. We conclude that there are changes in the functional network subserving divided attention in patients with AMCI as reflected in the attenuation of prefrontal cortical activation. These findings have implications for evaluating cognition in AMCI and also for monitoring the effects of future treatments in AMCI.

Keywords: amnestic mild cognitive impairment; Alzheimer's disease; divided attention; functional MRI; ANCOVA = analysis of covariance; BOLD = blood oxygenation level-dependent; cA = comparison attention task; fMRI = functional magnetic resonance imaging; MCI = mild cognitive impairment; RT = reaction time; SSQratio = sum of squares ratio

Journal Article.  7221 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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