Functional network changes may predict Alzheimer’s disease in elders
Magnetoencephalography (MEG) can detect functional network alterations accompanied by amyloid-β (Aβ) deposition in cognitively normal (CN) elderly adults before anatomical changes can be observed, a new study shows.
The investigators categorized 45 CN elderly adults (mean age 75.2±4.7 years) into two groups according to the presence of Aβ: those with Aβ deposits (CN+; n=13) and those without (CN-; n=32). All participants were subjected to neuropsychological batteries, MEG, magnetic resonance imaging (MRI), 11C-Pittsburgh compound B-positron emission tomography (PiB-PET) and 18F-fluorodeoxyglucose PET (FDG-PET).
Functional connectivity (FC) analysis using the MEG results showed that network connectivity between the precuneus was significantly diminished in the CN+ (0.443±0.024) than in the CN- (0.470±0.022; p<0.001) group.
In contrast, FC between the precuneus and right inferior parietal lobule was significantly greater in the CN+ group (delta band, 0.366±0.008; theta band, 0.288±0.015) than in the CN- group (delta band, 0.343±0.011; theta band, 0.265±0.009; p<0.001 for both bands).
FC between the precuneus and right inferior parietal lobule was significantly greater for the delta and theta bands in the CN+ (0.365±0.011 and 0.287±0.009, respectively) than in the CN- group (0.343±0.010 and 0.265±0.010, respectively; p<0.001 for both).
All of the FC variables were either positively or negatively significantly correlated with PiB mean standardized uptake value ratio within default mode networks indicating significant linear associations with cerebral amyloid depositions.
Notably, quantitative analyses of FDG-PET and MRI volumetric data showed that there was no significant difference between the CN+ and CN- groups. FDG-PET scores were not significantly correlated with FC values.