Age-related changes in neural control of posture

As we get older many physiological functions decline, including muscle strength, flexibility, and memory. Also in the aging brain there are changes, such as shrinkage of its volume. Since we need our brain to keep our balance while standing, it seems likely that these changes also affect our balance control. In this thesis we therefore aimed to investigate whether and how the role of the brain in balance control changes with aging and how this affects stance stability. For our study we used a TMS (transcranial magnetic stimulation) device with which we stimulated the brain of young and old adults during various balance tasks. The effect of this stimulation is a brief muscle contraction that allows us to measure the excitability of the brain. The results show that both young and old brains are more active during difficult compared with easier balance tasks. The good news is that the ability to adjust the brain activity to the balance task is not affected by age. However, the threshold is lower in old compared with young adults, meaning that old adults activate the brain in easier tasks. We also investigated whether the increased brain activation is the reason that old adults have more difficulty with dual-tasking than young adults. Although this hypothesis is often mentioned, our study suggests that this is incorrect. Overall, the findings of this thesis help us better understand why elderly are more unstable than young adults and therefore forms a basis for better fall prevention programs.