Affiliations: [a] Cyclotron Research Center, University of Liège, Liège, Belgium | [b] Greyou Medical, Constantine, Algeria | [c] Memory Center, CHU Liège, Liège, Belgium | [d] Neuropsychology Unit, University of Liège, Liège, Belgium | [e] Department of Psychology, University of Leuven, Leuven, Belgium
Correspondence:
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Correspondence to: Christine Bastin, Cyclotron Research Center, University of Liège, Allée du 6 Août, B30, 4000 Liège, Belgium. Tel.: +32 4 366 23 27; Fax: +32 4 366 29 46; E-mail: Christine.Bastin@ulg.ac.be.
Abstract: Alzheimer's disease (AD) is characterized by a progressive loss of controlled cognitive processes, and neuroimaging studies at early stages of AD provide an opportunity to tease out the neural correlates of controlled processes. Accordingly, controlled and automatic memory performance was assessed with the Process Dissociation Procedure in 50 patients diagnosed with questionable Alzheimer's disease (QAD). The patients' brain glucose metabolism was measured using FDG-PET. After a follow-up period of 36 months, 27 patients had converted to AD, while 23 remained stable. Both groups showed a similar decrease in controlled memory processes but preserved automatic processes at entry into the study. Voxel-based cognitive and metabolic correlations showed that a decrease in controlled memory processes was preferentially correlated with lower activity in the dorsomedial prefrontal and posterior cingulate cortices in very early AD patients. In stable QAD patients, reduced controlled performance in verbal memory correlated with impaired activity in the left anterior hippocampal structure. The results demonstrate the central role of a medial frontal-posterior cingulate network for controlled processing of episodic memory in the early stages of AD.
