Tract-Based Spatial Statistics Analysis of Diffusion Tensor Imaging in Older Adults After the PICMOR Intervention Program: A Pilot Study

Abstract

Diffusion tensor imaging (DTI) enables the investigation of white matter properties in vivo by applying a tensor model to the diffusion of water molecules in the brain. Using DTI metrics including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD), an attempt has been made to detect age-related alterations in the white matter microstructure in aging research. However, the use of comprehensive DTI measures to examine the effects of cognitive intervention/training on white matter fiber health in older adults remains limited. Recently, we developed a cognitive intervention program called Photo-Integrated Conversation Moderated by Robots (PICMOR), which utilizes one of the most intellectual activities of daily life, conversations. To examine the effects of PICMOR on cognitive function in older adults, we conducted a randomized controlled trial and found that verbal fluency task scores were improved by this intervention. Based on these behavioral findings, we collected in this pilot study diffusion-weighted images from the participants to identify candidate structures for white matter microstructural changes induced by this intervention. The results from tract-based spatial statistics analyses showed that the intervention group, who participated in PICMOR-based conversations, had significantly higher FA values or lower MD, AD, or RD values across various fiber tracts, including the left anterior corona radiata, external capsule, and anterior limb of the internal capsule, compared to the control group, who participated in unstructured free conversations. Furthermore, a larger improvement in verbal fluency task scores throughout the intervention was associated with smaller AD values in clusters, including the left side of these frontal regions. The present findings suggest that left frontal white matter structures are candidates for the neural underpinnings responsible for the enhancement of verbal fluency. Although our findings are limited by the lack of comparable data at baseline, we successfully confirmed the hypothesized pattern of group differences in DTI indices after the intervention, which fits well with the results of other cognitive intervention studies. To confirm whether this pattern reflects intervention-induced white matter alterations, longitudinal data acquisition is needed in future research.

Web-Based Group Conversational Intervention on Cognitive Function and Comprehensive Functional Status Among Japanese Older Adults: Protocol for a 6-Month Randomized Controlled Trial

“…Our voxel-based morphometric analysis also identified the candidate brain regions involved in the intervention mechanism, including the lateral prefrontal cortex [25]. Further, analysis using diffusion tensor imaging metrics suggested that left frontal white matter structures were candidates for white matter microstructural changes effected by the intervention [26]. Building on these findings, we have inferred that our conversational intervention may stimulate language-related function in the prefrontal lobe, serving as a potential mechanism underlying the observed effects .…”

“…The main outcome measure is cognitive function. Specifically, we hypothesized that the PICMOA may stimulate linguistic and executive functions through fundamental conversation activities based on the results of previous RCTs [22,23,27] and mechanistic hypothesis based on the explanatory investigation using multimodal MRI [24][25][26]. Thus, we will specifically focus on verbal fluency as the primary outcome, which may reflect linguistic and executive functions.…”

Effect of home-based group conversation intervention using smartphone application on cognitive health and psychological well-being of older adults with subjective cognitive concerns in Japan: a randomized controlled trial protocol

“…As a result of utilizing PICMOR in an RCT among healthy older adults, phonemic fluency was significantly improved by following a 30-min weekly session for 12 weeks, compared to the control group in which free group conversations were held in the same frequency (Otake-Matsuura et al, 2021 ). Moreover, our post-intervention multimodal magnetic resonance imaging (MRI) showed significant differences in brain metrics between the PICMOR and control groups, which could be associated with the beneficial effect of the intervention on phonemic fluency (Sugimoto et al, 2020 ; Sugimoto and Otake-Matsuura, 2022a , b ). For example, compared to the control group, the intervention group had higher resting-state functional connectivity between the left inferior frontal gyrus, one of the most important brain regions for verbal fluency, and right temporal pole which has been associated with semantic processing (Sugimoto et al, 2020 ).…”

“…Additionally, resting-state functional connectivity between these regions was positively correlated with the enhanced phonemic fluency score measured by a neuropsychological test. Moreover, we attempted to elucidate neural underpinnings responsible for the intervention-induced enhancement of verbal fluency by analyzing structural characteristics, including brain volume (Sugimoto and Otake-Matsuura, 2022a ) and diffusion tensor imaging (DTI) metrics (Sugimoto and Otake-Matsuura, 2022b ).…”

Diffusion MRI Fiber Tractography and Benzodiazepine SPECT Imaging for Assessing Neural Damage to the Language Centers in an Elderly Patient after Successful Reperfusion Therapy

“…Diffusion MRI tractography performed 2 weeks after admission revealed partial injury to the left arcuate fasciculus, although no new lesions or atrophic changes in the cortical areas were observed in the structural MRI ( Figure 3 A,B). The images were preprocessed using tools and scripts provided by MRtrix33 [ 12 ]. Regarding the diffusion tensor imaging–fractional anisotropy (DTI-FA) map, the FA signals from the left Broca’s area projecting to the perisylvian cortex and superior longitudinal fasciculus could not be reconstructed, whereas those from Wernicke’s area were similar to those from the contralateral side ( Figure 3 C,D).…”