Effect of the interaction between BDNF Val66Met polymorphism and daily physical activity on mean diffusivity

Numerous studies have reported that the Met allele of the brain-derived neurotrophic factor (BDNF) gene polymorphism reduces neural plasticity. A reduction in mean diffusivity (MD) in diffusion tensor imaging (DTI) characteristically reflects the neural plasticity that involves increased tissue components. In this study, we revealed that the number of Met-BDNF alleles was negatively associated with MD throughout the whole-brain gray and white matter areas of 743 subjects using DTI and whole-brain multiple regression analyses. Within the same sample, the region of interest analysis revealed that the number of Met-BDNF alleles significantly and positively correlated with the mean FA value in the body of the corpus callosum. In addition, we observed interaction effects between BDNF Val66Met polymorphism and daily physical activity levels on MD, but not FA, in significant clusters of the bilateral hemisphere (n = 577 subjects). Post-hoc multiple regression analyses revealed that after correcting for confounding variables, there was a significant negative correlation between the physical activity level and mean MD of the whole brain in the Val/Val group [standardized partial regression coefficient (β) = -0.196, P = 0.005, t = -2.825], but not in the Val/Met (β = 0.050, P = 0.412, t = 0.822) and Met/Met groups (β = 0.092, P = 0.382, t = 0.878). These results underscore the importance of the interaction between physical activity and the BDNF Val66Met polymorphism, which affects the plasticity of neural mechanisms.

Description of novel instrumented analysis of the Four Square Step Test with clinical application: A pilot study

BACKGROUND

Falls are a common problem for adults in the United States raising concerns about injuries and the resulting economic burden. As a result, it is critical to develop objective measures to assess dynamic balance and the track progress related to interventions or disease progression over time.

RESEARCH QUESTION

Are there differences in balance between individuals in the community, individuals post-stroke, persons with Multiple Sclerosis (MS), and individuals living with Parkinson's Disease (PD) as measured with a new instrumented Four Square Step Test (i-FSST)?

METHODS

The i-FSST was utilized to assess dynamic balance in 41 individuals (11 community dwelling adults and 10 individuals in each group of persons post stroke, with PD, and with MS). Outcome data including the overall duration of the FSST as well unique temporal-spatial stepping patterns through the test, timing of transitions between each quadrant, and the time in each quadrant prior to transitioning.

RESULTS

One-way ANOVAs were conducted to determine whether i-FSST duration, Over Double Support (ODS), and Changes in Main Support (CMS) differed by participants' groups. There was a significant difference between groups in test Duration (F = 9.56, P =  .000), ODS (F = 15.71, P =  .001), and CMS (F = 7.03, P =  .001). Further differences in these variables were found between various groups using Bonferroni post-hoc testing.

SIGNIFICANCE

The i-FSST is an innovative and potentially beneficial tool for quantitatively measuring the dynamics that occur in the traditional FSST including a general measure of dynamic balance as well as transition times and stability during the test. This technology can provide objective data on stability, weight shifting, and weight acceptance that may guide interventions and further assessment.