3 Results
3.1 Participant
characteristics
Demographic and clinical characteristics of all participant groups are
summarized in Table 1. The groups did not differ in age, sex and
education. Healthy controls and patients showed significant differences
in clinical scores. Comparing both patient groups, we found significant
differences in medication status. Both patient groups did not differ in
duration of illness and BDI-II- and BAI scores.
3.2 Resting state functional connectivity
Table 3 summarizes the network aberrations found for the three examined
networks. Figure 1 illustrates the clusters found in their respective
networks. Comparing MDD+AD and HC, MDD+AD showed a significantly reduced
RSFC for the VAN with both the ECN and the DMN. No alteration in RSFC of
the ECN and DMN could be found.
Between the DMN and the VAN, the right posterior cingulate cortex seed
of the DMN showed a significantly decreased RSFC with regions in the VAN
(RPCC to: right middle cingulate and paracingulate gyrus, t =
4.64, pcorr = .015; right middle cingulate and
paracingulate gyrus, t = 5.86, pcorr =
.011) and the left and right dorsal anterior insula of the VAN showed
significantly decreased RSFC with regions in the DMN (RdaIns to: right
anterior cingulate cortex, pregenual parts, t = 5.21,pcorr = < .001; LdaIns to: left
anterior cingulate cortex, pregenual parts, t = 5.80,pcorr = <.001).
Between the ECN and the VAN, the left dorsomedial prefrontal cortex and
the left dorsolateral prefrontal cortex of the ECN showed significantly
decreased RSFC with the VAN (LdmPFC to: left middle cingulate and
paracingulate gyri, t = 5.06, pcorr =
.002; LdlPFC to: right middle cingulate and paracingulate gyri, t= 4.53, pcorr = .001). The left dorsal anterior
insula of the VAN showed significantly reduced RSFC with the ECN (LdaIns
to: right superior frontal gyrus, dorsolateral parts, t = 4.36,pcorr = .024).
The ECN showed significantly reduced RSFC on the within-network level
(RdmPFC to: left middle frontal gyrus, t = 4.84,pcorr = .006).
We could not find any significant differences for the group comparisons
including the MDD group (MDD – HC and MDD – MDD+AD).
3.3 Post-hoc regression
analysis
Outcomes of regression analysis for the relationship of severity of
symptoms as measured by BDI-II and BAI total scores and RSFC values of
the found clusters within the patient group (MDD and MDD+AD) are shown
in Table 3. No cluster showed a significant connection.
Furthermore, we did not find a significant effect of medication status
on RSFC-values for the clusters that were found to be significant in
group-wise analysis.