Alterations in the integrity of cortical and subcortical circuits in AD and MCI: Connectivity study in rs‐fMRI.
Keveen Rodriguez, Claudia Aponte, Carlos Andrés Andrés Tobón Quintero, John F Ochoa, Aura C Puche, Maria Jose Hidalgo- Psychiatry and Mental health
- Cellular and Molecular Neuroscience
- Geriatrics and Gerontology
- Neurology (clinical)
- Developmental Neuroscience
- Health Policy
- Epidemiology
Abstract
Background
rs‐FC has been altered in AD continuum with hyper‐hypoconnectivity patterns attributed not only to regional changes, but to disruption of functional integration or aberrant connectivity between cortical and subcortical brain regions . This study seeks to find connectivity patterns in MCI and AD with a different network extraction approach taking each network as a whole and not separated into ROIs.
Methods
rs‐fMRI data from ADNI3 and OASIS3 of 64/85 AD/Control subjects, 57/59 MCI/Control subjects from both repositories were preprocessed with the CONN toolbox. Resting state networks (RSN) were extracted by cGICA using GIFT toolbox (semi‐blind INFOMAX) with 300 ROI Set template with 14 RSN. A non parametric 2‐sample t‐test was applied using the SnPM tool, all analyses in SnPM were performed using 10000 random permutations and the anatomical association of each reported cluster is extracted from the AAL atlas using the xjView tool . Regions that had statistically significant clusters with p FWE<0.001 and with k> = 100 voxels were analyzed.
Results
There were alterations in regions of every network for each groups comparison (p < 0.001). Several ROI were repeatedly altered in analyzed RSN, temporal pole, MTG, STG, cerebellar crus, OFC, PCC, MCC, precuneus, AG, SMG, SPL, IPL, SFG, MFG, IFG, thalamus, FG and posterior cerebellar lobe. Decreased/increased activation area, changes in activation intensity and reorganization of activation areas, specially reduced activation areas in AD and greater activation areas in MCI. The RSN with more changes in connectivity patterns were DMN, DAN/VAN, MTL, SAL and FPN.
Conclusion
Changes in connectivity in MCI and AD show reorganization of RSN related to enlargement, reduction or displacement of activation areas, the greatest amount of change was observed in MCI with increases in activation areas and in AD a general decrease in activation areas was observed, these alterations are consistent with the inverted u‐pattern that has been described in other studies . The common ROI we found altered had been related with accumulation and aggregation of p‐Tau and βA and this could be an explanation of connectivity changes duet to the neurodegeneration and synaptic dysfunction caused by this proteins