Affiliations: [a] Alzheimer Memorial Center, Department of Psychiatry and Psychotherapy, Ludwig-Maximilian University, Munich, Germany | [b] Discipline of Psychiatry, School of Medicine, Trinity College Institute of Neuroscience, Trinity College Dublin, The Adelaide and Meath Hospital incorporating The National Children's Hospital (AMiNCH), Dublin, Ireland | [c] Institute for Clinical Radiology, Ludwig-Maximilian University, Munich, Germany | [d] Department of Psychiatry and Psychotherapy, Ludwig-Maximilian University, Munich, Germany | [e] Department of Psychiatry and Psychotherapy, JW Goethe University, Frankfurt, Germany
Correspondence:
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Correspondence to: Arun L W Bokde, PhD, Discipline of Psychiatry, School of Medicine & Trinity College Institute of Neuroscience, Lloyd Building, Dublin 2, Ireland. Tel.: +353 1 896 4104; Fax: +353 1 896 3183; E-mail: Arun.Bokde@tcd.ie.
Abstract: In subjects with mild cognitive impairment (MCI), memory disorders indicate a high risk for conversion to Alzheimer's disease (AD). The objective of this study was to delineate the differences in brain activation between amnestic MCI and age-matched healthy controls (HC) during a verbal working memory task. The verbal working memory task was a delay match to sample design. Brain activation was measured using functional magnetic resonance imaging. There were 8 subjects in each group and were matched for performance. The task was analyzed as an event-related design. Group differences were calculated using Analysis of Covariance (ANCOVA) with statistical significance at p<0.05 corrected. Both groups activated a wide network in the posterior and frontal areas of the brain. There was higher activation in the parietal and frontal lobes in the MCI compared to the HC during the maintenance phase. There were no areas in the HC that activated higher than the MCI subjects. Response time in the task in the HC group was correlated to the left hippocampus during encoding phase and to the parietal and frontal areas during the recall phase. In the MCI group, there was strong correlation to the inferior and middle temporal gyrii during encoding, the middle frontal gyrus during the maintenance phase, and hippocampus during recall phase. The activation differences between groups may be compensatory mechanisms within the MCI group for the effects of the putative AD neuropathology. This has been the first study that has examined verbal working memory in MCI.
Keywords: Face matching, functional magnetic resonance imaging, location matching, object matching, visual system
