Table 2.
Intervention studies of the effect of physical activity, diet, cognitive training and meditation on WM microstructure
| Sample | Intervention | DTI | Main findings | |
|---|---|---|---|---|
| Physical activity | ||||
| Voss et al. (2013) | 70 older adults; aged 55–80 y | One year of either (1) walking or (2) flexibility, toning, and balance training | TBSS and ROI (3T) | No significant differences between the groups, but increased aerobic fitness was associated with significant increases in prefrontal, parietal, and temporal FA in the walking group only (controlled for age, sex, and intervention attendance). |
| Burzynska et al. (2017) | 174 older adults; aged 60–79 y | 6 mo of either (1) dance, (2) walking, (3) walking + nutrition, (4) active control group (stretching and toning) | ROI on TBSS skeleton (3T) | A significant time by group interaction was found for the fornix, with higher FA for the dance group, but lower FA for other groups. This effect was driven by RD and MD, which increased to a lesser extent in the dance group compared with the other groups. |
| Fissler et al. (2017) | 39 older adults at risk of dementia; aged >55 y | 10-wk intervention of either (1) physical exercise: aerobic, strength, coordination, balance, and flexibility elements, or (2) cognitive training, or (3) passive control | ROI (1.5 T) | No effect of physical exercise on FA compared with control, but fitness level was positively associated with fornix FA at the baseline. |
| Cognitive training | ||||
| Engvig et al. (2012) | 41 older adults; aged 42–77 y | 8-wk of either (1) memory training, or (2) control group: living as usual | TBSS (1.5 T) | A decrease in FA in the control group compared to the memory training group was reported in areas overlapping the left anterior TR, IFOF, UF, and SLF (controlled for baseline measures). |
| Strenziok et al. (2014) | 42 older adults; mean age 69 y | 6 wk of either: (1) Brain Fitness (BF): auditory perception, (2) Space Fortress (SF): visuomotor/working memory, or (3) Rise of Nations (RON): strategic reasoning | TBSS (3T) | An increase in AxD was found in the Brain Fitness group compared with the other groups from the baseline to follow-up. Increased AxD in BF compared with SF group was reported in: IFOF, ILF, CC, and posterior TR. AxD additionally increased in the SLF, IC, and AR in BF compared with the RON group. |
| Lampit et al. (2015) | 12 older adults; aged >65 y | 12 wk of either (1) multi-domain cognitive training, or (2) active control: viewing videos and answering questions | TBSS (3T) | No significant differences between the groups over time. |
| Chapman et al. (2015) | 37 older adults; aged 56–71 y | 12 wk of either: (1) cognitive training: gist reasoning, or (2) wait-list control | Tractography and ROI (3T) | Increased FA in the UF of the cognitive training group compared with the control group. |
| Cao et al. (2016) | 48 older adults; aged 65–75 y | 12 wk of either (1) multidomain cognitive training, (2) single-domain cognitive training: reasoning, (3) control group. | TBSS (3T) | The control group had higher RD and MD, and lower FA in the posterior CR compared with the multidomain cognitive training group. No differences in DTI measures were found from the baseline to follow-up between the multi- and single-domain cognitive training groups, nor the single-domain and control group (controlling for age, sex, education, and baseline DTI measures). |
| Antonenko et al. (2016) | 25 older adults; age 56–78 y | 3 d of object location training | ROI (3T) | Higher FA and significantly lower MD in the fornix, but not UF or cingulum, following 3-d of object location training. |
| de Lange et al. (2016) | 104 older adults, mean age 73.5 y | 10 wk of either (1) memory training, (2) active control: popular scientific lectures, (3) passive control | TBSS (3T) | Memory performance improved significantly in the memory training group only. Furthermore, negative relationships between memory improvement and MD, AxD, and RD were found in, for MD: anterior CC, the left anterior AR, and the right IFOF, for AxD: right IFOF, and for RD: anterior CC (controlled for age, sex and motion). |
| de Lange et al. (2017) | 111 older adults; mean age 73 y | 10 wk of either (1) memory training, (2) active control: popular scientific lectures, or (3) passive control | TBSS (3T) | The memory training group, relative to the control groups, showed an increase in FA and decrease in MD, RD, and AxD in areas overlapping the CC, the CST, the cingulum, the SLF and the anterior TR (controlled for age, sex, motion, baseline WM values and WM hypointensities). |
| Fissler et al. (2017) | 39 older adults at risk of dementia; aged >55 | 10-wk intervention of either (1) physical exercise, (2) cognitive training: auditory processing and working memory, (3) passive control | ROI (1.5 T) | No effect of cognitive training on FA compared with the control group, but cognitive training skills at the baseline were associated with FA. |
| Diet | ||||
| Witte et al. (2014) | 65 older adults; aged 50–75 y | 26-wk intervention of (1) either fish oil (2.2 g/d LC-n3-FA) or (2) placebo | TBSS (3T) | Fish oil supplementation led to significant increases FA as well as decreases in MD and RD, in various areas: the anterior CC, the UF, the IFOF and SLF. |
| Meditation | ||||
| Tang et al. (2012) |
Study 1: 45 young adults; mean age 20.58 y Study 2: 68 young adults; mean age 20.52 y |
Study 1: 4 wk of either (1) integrative body-mind training (IBMT), or (2) relaxation training Study 2: 2 wk of either (1) IBMT, or (2) relaxation training |
TBSS (3T) |
Study 1: Increased FA and lower AxD and RD in the anterior and superior CR, anterior CC and SLF after IBMT but not relaxation training. Study 2: Decrease in AxD only in the CC, CR, SLF, posterior TR, and sagittal stratum following IBMT but not relaxation training. |
| Hölzel et al. (2016) | 46 adults; mean age ∼32 y | 8-wk of either (1) mindfulness-based stress reduction training, or (2) waitlist control | Tractography (3T) | Increased FA in right UF following meditation training, but no change in the control group and no significant group by time interaction. |
Key: AD, axial diffusivity; AR, acoustic radiation; CC, corpus callosum; CR, corona radiata; CRT, corticospinal tract; CT, cognitive training; DTI, diffusion tensor imaging; FA, fractional anisotropy; IBMT, integrative body-mind training; IC, internal capsule; ILF, inferior longitudinal fasciculus; IFOF, inferior fronto-occipital fasciculus; MD, mean diffusivity; RD, radial diffusivity; ROI, region of interest; SLF, superior longitudinal fasciculus; TBSS, tract-based spatial statistics; TR, thalamic radiation; UF, uncinate fasciculus.