Changes in Neural Connectivity and Memory Following a Yoga Intervention for Older Adults: A Pilot Study

Abstract

Background: No study has explored the effect of yoga on cognitive decline and resting-state functional connectivity.

Objectives: This study explored the relationship between performance on memory tests and resting-state functional connectivity before and after a yoga intervention versus active control for subjects with mild cognitive impairment (MCI).

Methods: Participants ( ≥ 55 y) with MCI were randomized to receive a yoga intervention or active "gold-standard" control (i.e., memory enhancement training (MET)) for 12 weeks. Resting-state functional magnetic resonance imaging was used to map correlations between brain networks and memory performance changes over time. Default mode networks (DMN), language and superior parietal networks were chosen as networks of interest to analyze the association with changes in verbal and visuospatial memory performance.

Results: Fourteen yoga and 11 MET participants completed the study. The yoga group demonstrated a statistically significant improvement in depression and visuospatial memory. We observed improved verbal memory performance correlated with increased connectivity between the DMN and frontal medial cortex, pregenual anterior cingulate cortex, right middle frontal cortex, posterior cingulate cortex, and left lateral occipital cortex. Improved verbal memory performance positively correlated with increased connectivity between the language processing network and the left inferior frontal gyrus. Improved visuospatial memory performance correlated inversely with connectivity between the superior parietal network and the medial parietal cortex.

Conclusion: Yoga may be as effective as MET in improving functional connectivity in relation to verbal memory performance. These findings should be confirmed in larger prospective studies.

Keywords: Aging; cognitive decline; memory training; mild cognitive impairment; mind-body; older adults; subjective memory complaints; yoga.

Fig.1

Flow diagram of participants through trial. ^aDue to lack of interest in the intervention or inability to commit to study schedule.

Fig.2

Changes in functional connectivity within the default mode network correlated with improved verbal memory performance. A) The default mode network (DMN) is displayed in yellow on a template brain in neurological convention. Regions that exhibited significant correlations between changes in DMN connectivity and changes in HVLT delayed recall are shown in red (z >  2.3, p <  0.05, corrected). All correlations were positive, and significant clusters included the pregenual anterior cingulate cortex (ACC), frontal medial cortex (FMC), posterior cingulate cortex (PCC), middle frontal gyrus (MFG), and lateral occipital cortex (LOC). B) Scatter plots indicate positive correlations in the clusters displayed in A in yoga (YOG, blue) and memory enhancement training (MET, red) groups. Trendlines are plotted for each group; dashed lines indicate trendlines without the outlier (marked with a black circle) for the yoga group.

Fig.3

Changes in functional connectivity within the language network correlated with improved verbal memory. A) The language resting-state network is displayed in yellow on a template brain in neurological orientation. A single region in the left inferior frontal gyrus (L IFG) showed a significant positive correlation between changes in language-network connectivity and improved verbal memory measured with the Hopkins Verbal Learning Test (HVLT). This region is displayed in red (z <  2.3, p <  0.05, corrected). B) A scatter figure displays the positive correlation for the L IFG cluster shown in A for yoga (YOG, blue) and memory enhancement training (MET, red) groups. Trendlines are displayed for each group, including a dashed line for a trendline with an outlier (circled in black) removed for the yoga group.

Fig.4

Changes in functional connectivity within the superior parietal network correlated with changes in visuospatial memory. A) The superior parietal resting-state network is displayed in yellow on a template brain. A single region near the pre- and post-central gyri (PCG) showed significant negative correlation between changes in connectivity with the superior parietal network and changes in visuospatial memory measured by the Rey-Osterrieth Complex Figure Test (Rey-O). This cluster is displayed in blue (z <  2.3, p <  0.05, corrected). B) A scatter figure displays the negative correlation for the PCG cluster displayed in A for the yoga (YOG, blue) and memory enhancement training (MET, red) groups. Trendlines are displayed for each group.