Impact of Tai Chi on global connectivity in geriatric depression

Abstract

<h3>Introduction</h3> Depression is generally associated with dysconnectivity among brain regions. Mind-body interventions such as Tai Chi can improve stress, and thus, comprise a promising adjunct treatment to antidepressants. We tested the effect of twelve weekly Tai Chi lessons on global connectivity in older depressed adults (aged >60 years). <h3>Methods</h3> Forty older adults with major depressive disorder under concurrent antidepressant treatment were randomized to receive Tai Chi training (N=21; 17 women; age, 67.1±7.4 years) or health education (N=19; 15 women; age, 68.2±5.6 years), and completed baseline and 12-week follow-up resting state magnetic resonance imaging scans. Fine-grained parcellation of the brain into 718 cortical and subcortical parcels, with each parcel assigned to one of 12 major networks, was performed using the CAB-NP atlas. Pairwise correlations between parcel timeseries were computed, and the change in connectivity (post–pre) was submitted to general linear modeling, with correction for multiple comparisons (1000 permutations; false discovery rate) and adjustment for sex and age. <h3>Results</h3> There were few significant increases with health education (∼0.03% of ∼257K pairwise connections; post vs pre). In the Tai Chi group, connectivity changes mainly reflected increased connectivity (∼0.3% of all pairwise connections; post vs pre), with the increase in connectivity reaching significance in the comparison between groups (Tai Chi post-pre vs control post-pre) for 194 connections, which were highly concentrated (48/194; 25%) within the default mode network (DMN; Figure 1), followed by connections between DMN and frontoparietal network regions (12/194; 6%). Within-DMN connections that significantly increased with Tai Chi and showed a significant group difference in the increase in connectivity are shown in Figure 1. The 718 nodes of the CAB-NP atlas are shown in the figure, with regions assigned to the DMN in purple and regions assigned to other networks in blue. <h3>Conclusions</h3> Tai Chi as an adjunct to antidepressants is effective in reorganizing the brain toward greater global connectivity, especially affecting DMN connectivity, in older depressed adults. DMN within-network connectivity has been implicated in depression, mainly in terms of dysconnectivity, and connectivity between the DMN and a subsystem of the frontoparietal control network is thought to be involved in the regulation of introspective processes. Our previous study suggested that symptom improvement with combined pharmacological treatment is associated with increased connectivity of core DMN nodes. The present study further supports the importance of the DMN in depression, and suggests that non-pharmacological adjuncts can also enhance DMN functional reorganization in geriatric depression. <h3>Funding</h3> Sponsored by NIH grant AT008383 and National Center for Advancing Translational Science (NCATS) UCLA CTSI Grant Number UL1TR001881.