Anosognosia in Alzheimer disease: Disconnection between memory and self networks

This study aims at improving our understanding of the neural mechanisms underlying anosognosia of memory deficits in AD by combining measures of regional brain metabolism (resting‐state FDG‐PET) and intrinsic connectivity (resting‐state fMRI).
Methods. Twenty‐three patients diagnosed with probable AD based on clinical and biomarker data, and thirty matched healthy control subjects were recruited in this study. An anosognosia index (difference between subjective and objective memory scores) was obtained in each participant. Resting‐state FDG‐PET for glucose metabolism measurement and resting‐state fMRI for intrinsic connectivity measurement were also performed. AD and control groups were compared on behavioral data, and voxel‐wise correlations between anosognosia and neuroimaging data were conducted within the AD group.
Results. AD patients underestimated their memory deficits. Anosognosia in AD patients correlated with hypometabolism in orbitofrontal (OFC) and posterior cingulate (PCC) cortices. Using OFC and PCC as seed regions, intrinsic connectivity analyses in AD revealed a significant association between anosognosia and reduced intrinsic connectivity between these regions as well as with the medial temporal lobe.
Interpretation. Anosognosia in AD is due not only to functional changes within cortical midline structures involved in self‐referential processes (OFC, PCC), but also to disconnection between these regions as well as with the medial temporal lo...

Source: Annals of Neurology - June 1, 2015 Category: Neurology Authors: Audrey Perrotin, Béatrice Desgranges, Brigitte Landeau, Florence Mézenge, Renaud La Joie, Stéphanie Egret, Alice Pélerin, Vincent de la Sayette, Francis Eustache, Gaël Chételat Tags: Research Article Source Type: research