Cognitive reserve modulates neural responses in subjective and mild cognitive impairment

Abstract

Cognitive reserve (CR) has been defined as a set of skills and repertoires, characterized by personal lifestyle and habits and is considered a protective factor against cognitive impairment (Scarmeas et al.,2003, Stern et al., 2009), particularly in the earlier stages. Indeed, a higher CR may be associated to a more efficient utilization of brain networks, as suggested by the more focused task-related neural responses found in functional magnetic resonance imaging (fMRI) studies in healthy individuals (Bernardi et al., 2011). Here we aim to determine the correlation between CR scores and patterns of brain response in both subjective cognitive impairment (SCI) and mild cognitive impairment (MCI) subjects, while they perform a spatial attention task. Thirty-one MCI (14M, 74.0 yr ± 5.2) and 24 SCI (13M, 72.0 yr ± 5.8) patients underwent neuropsychological assessment and a fMRI experimental protocol (GE 1.5 T, GRE-EPI, TR 2.5s, TE 50ms, 33 Axial Slices, 3mm isotropic voxel, FA 90°, 180 volumes) during a visuo-spatial attention task (Bernardi et al., 2011). Cognitive Reserve Index (CRIq, Nucci et al., 2001) scores were correlated (Cox et al., 1996) to task-related brain responses, considering age as a confounding factor, after processing fMRI data at an individual and group level. CRIq scores negatively correlated with neural responses (p<0.05 cluster corrected) in the task-related bilateral parietal areas (R 2 =0.365) within the spatial dorsal stream, the superior, middle and inferior frontal cortex (R 2 =0.373), and the posterior cingulate cortex (R 2 =0.28).