Neural correlates of cognitive and functional decline in alzheimer's disease: a community memory clinic cohort

Impairment in activities of daily living (ADL) is a fundamental feature of Alzheimer's disease (AD). This study explores correlation between cognitive and functional impairment and grey matter (GM) volumes in people with mild cognitive impairment (MCI) and AD. 78 patients with amnestic MCI (n=44) and AD (n=34) from a community memory clinic underwent clinical assessment and magnetic resonance imaging. T1-weighted images were obtained using the Siemens Avanto 1.5 T scanner and pre-processed with SPM12 VBM pipeline. The variables of interest (cognitive and functional impairment) were measured using the Addenbrooke's cognitive examination-revised (ACE-R) and Bristol activities of daily living (BADL). All comparisons were adjusted for age and gender. The statistical analysis was carried out in SPM12. See table 1 for demographic, cognitive and functional data. GROUP COMPARISON As predicted, AD patients showed widespread areas of GM tissue loss compared to MCI, particularly in medial-temporal and parietal areas (Fig.1). CORRELATION WITH ACE-R GM was correlated positively with ACE-R in anterior and posterior cingulate, supramarginal/angular gyrus, parahippocampal gyrus (p<0.001) (Fig.2). The following clusters were statistically significantly associated applying family-wise error (FWE) correction at cluster level: middle/inferior temporal gyrus (p<0.001), temporo-occipital cortex near fusiform gyrus (p=<0.001), frontal pole/anterior cingulate and right hippocampus/parahippocampal gyrus (p<0.001) CORRELATION WITH BADL GM was correlated negatively with BADL in frontal and parietal areas, and in the left thalamus. The strongest correlations were in the frontal pole (bilaterally) and the right opercular/insular cortex (although they only approached statistical significance after FWE correction, with p∼0.08) (Fig.3). Group comparison and ACE-R correlation analysis replicate previous reports. However, it is interesting to observe how the areas of GM volume correlating with ACE-R overlap with the default mode network (DMN). Although less strongly correlated, the associations between BADL and GM volume are located predominantly in frontal areas, but also in the opercular/insular cortex, an area implicated with self-awareness, body ownership and social emotions. Grey matter volume differences between AD and MCI patients. Grey matter volume correlation with ACE-R. Grey matter volume correlation with BADL.