title: Memory is Not Enough: The Neurobiological Substrates of Dynamic Cognitive Reserve.
abstract: Changes in the residual memory variance are considered as a dynamic aspect of cognitive reserve (d-CR). We aimed to investigate for the first time the neural substrate associated with changes in the residual memory variance overtime in patients with amnestic mild cognitive impairment (aMCI). Thirty-four aMCI patients followed-up for 36 months and 48 healthy elderly individuals (HE) were recruited. All participants underwent 3T MRI, collecting T1-weighted images for voxel-based morphometry (VBM). They underwent an extensive neuropsychological battery, including six episodic memory tests. In patients and controls, factor analyses were used on the episodic memory scores to obtain a composite memory score (C-MS). Partial Least Square analyses were used to decompose the variance of C-MS in latent variables (LT scores), accounting for demographic variables and for the general cognitive efficiency level; linear regressions were applied on LT scores, striping off any contribution of general cognitive abilities, to obtain the residual value of memory variance, considered as an index of d-CR. LT scores and d-CR were used in discriminant analysis, in patients only. Finally, LT scores and d-CR were used as variable of interest in VBM analysis. The d-CR score was not able to correctly classify patients. In both aMCI patients and HE, LT1st and d-CR scores showed correlations with grey matter volumes in common and in specific brain areas. Using CR measures limited to assess memory function is likely less sensitive to detect the cognitive decline and predict the evolution of Alzheimer's disease. In conclusion, d-CR needs a measure of general cognition to identify conversion to Alzheimer's disease efficiently.
authors.affiliation: Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Serra
authors.affiliation: Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Bruschini
authors.affiliation: Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
authors.forename: Carlotta
authors.initials: C
authors.lastname: Di Domenico
authors.affiliation: Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
authors.forename: Giulia Bechi
authors.initials: GB
authors.lastname: Gabrielli
authors.affiliation: Institute of Neurology, Catholic University, Rome, Italy.
authors.forename: Camillo
authors.initials: C
authors.lastname: Marra
authors.affiliation: Department of Clinical and Behavioural Neurology, Santa Lucia Foundation, IRCCS, Rome, Italy.|Department of Systems Medicine, University of Rome 'Tor Vergata', Rome, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Caltagirone
authors.affiliation: Brighton & Sussex Medical School, CISC, University of Sussex, Brighton, Falmer, East Sussex, UK.
authors.forename: Mara
authors.initials: M
authors.lastname: Cercignani
authors.affiliation: Neuroimaging Laboratory, Santa Lucia Foundation, IRCCS, Rome, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Bozzali
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging*; D001931:Brain Mapping; D060825:Cognitive Dysfunction / Q000473:pathology* / Q000503:physiopathology*; D058245:Cognitive Reserve / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D061212:Memory, Episodic; D008875:Middle Aged; D009483:Neuropsychological Tests; D011569:Psychiatric Status Rating Scales
keywords: Dynamic cognitive reserve; memory; mild cognitive impairment; voxel-based morphometry