Coupling of Structural and Functional Connectivity in Middle-Aged Offspring of Patients with Late-Onset Alzheimer?s Disease (LOAD)

SANCHEZ, STELLA M; DUARTE ABRITTA, BARBARA; ABULAFIA, CAROLINA; PALLAVICINI, CARLA; TAGLIAZUCCHI, ENZO; FIORENTINI, LETICIA; GUINJOAN, SALVADOR M; VILLAREAL, MIRTA F.

Conferencia; Society of Biological Psychiatry; 2021

In this work we analysed a sample of healthy subjects who are at risk of developing LOAD because of their family history. According to previous works, we know that structural connectivity and functional connectivity are changed in this sample when compared with a group of control subjects without family history of any neurodegenerative disease. This time, in order to know if structural connectivity could explain or modulate the functional aspect of the brain, we seek a metric which combines both connectivities. To achieve this, we processed functional MRI data to obtain ROI-wise matrices for functional connectivity. On the other hand, we also analysed diffusion MRI data to build a tractogram for structural connectivity. We defined the coupling metric as the Spearman?s correlation coefficient that associated these two data and we explored this coupling at three different levels: The first one, per subject: We collapsed all connectivity values (SC and FC) in only one coupling metric per subject. We built one vector per group. The second one, per brain region: In this case we obtained one value per brain region. Let´s think in only one region, so for SC we added all streamlines generated from this region, and for FC we averaged all Pearson´s coefficients per subject. Finally, we correlated these collapsed structural and functional values for all subjects in each group. The third level, is per connection: We correlated each structural connectivity value with its functional counterpart obtaining a coupling metric per connection. In addition, we selected only connections that are presented in (at least) 50% of the subjects. We only obtained significant results at connection level. We observed that the CS group presented significant coupling between connectivities in 20 pairs of connection while in the offspring group only in 10 connections. In this line, the offspring group did not yield significant coupling in connections with, for example, precuneus, entorhinal cortex and hippocampus, known regions that are affected by AD. This suggests a potential deficit in the association between connectivities in subjects who are at risk of developing LOAD.