The complexity of walking. Cognitive control of gait in aging and Parkinson's disease

Many older adults, especially those with Parkinson’s disease, experience difficulties during walking. Mainly complex situations that require another action next to walking itself (talking, thinking or navigating) often lead to falls. In this thesis, we investigated the neural causes underlying these walking difficulties (by using fNIRS and fMRI). Interesting results were that older adults with Parkinson’s disease did not show increased activity in frontal brain areas during complex compared to simple walking. Walking probably takes much attention (reflected in increased frontal activity), which cannot be further increased in more complex situations. Besides, we found that deep within the brain (in the putamen), older adults with Parkinson’s disease showed altered activity during complex situations. Possibly, Parkinson‘s disease caused brain networks that normally are nicely segregated to be intertwined. This could be another mechanism underlying the inability to combine two tasks. In older adults without Parkinson’s disease, we did not find altered brain activity. Especially in Parkinson’s disease, the results of this thesis provide new insights and opportunities for development of therapies to improve walking.