Altered connectivity among the triple brain networks in patients with mild cognitive impairment: a source-based morphometry study with a large elderly population.

PURPOSE

Previous research indicates brain network alterations in the default mode network (DMN), salience network (SN), and central-executive network (CEN) in individuals with mild cognitive impairment (MCI). However, replication has been inconsistent due to small, varied samples. We aimed to explore intra- and inter-networks alternations among DMN, SN, and CEN in individuals with MCI using multivariate source-based morphometry (SBM) with a larger, population-based sample.

MATERIALS AND METHODS

This cross-sectional study included 1,997 participants (median age: 69 years; 61.9% female) who underwent three-dimensional (3D) T1-weighed imaging with 3 T magnetic resonance imaging (MRI). They were classified into 1,236 healthy controls (HC) and 761 individuals with MCI. SBM was used to extract triple brain networks as structural networks, and Z-scores were calculated. Intra-network comparisons of DMN, SN, and CEN between HC and MCI groups were conducted using logistic regression analysis. Inter-network comparisons among the triple brain networks were performed using structural equation modeling (SEM).

RESULTS

Connectivity (median Z score) of each network was lower in the MCI group than in the HC group: DMN (0.08 vs. - 0.12), SN (0.08 vs. - 0.23), and CEN (0.07 vs. - 0.06). Logistic regression showed significant association of SN connectivity with MCI (odds ratio 0.862, p < 0.05). SEM analysis revealed a significant group difference in the model where SN mediated input from CEN to DMN.

CONCLUSION

We found altered network patterns in individuals with mild cognitive impairment, suggesting a transformation in network connectivity among DMN, SN, and CEN, particularly compensating for degraded SN connectivity.