MedicalResearch.com Interview with:
Prof. Jeffrey Hausdorff PhD
Director of the Center for the Study of Movement, Cognition and Mobility
Full Professor in the Sackler School of Medicine and Sagol School of Neuroscience
Tel Aviv Medical Center
MedicalResearch.com: What is the background for this study?
Response: Many people with Parkinson’s disease suffer from a disturbing symptom referred to as “freezing of gait”. When freezing occurs, the person’s feet inexplicably become stuck to the floor and he or she is unable to move forward, despite efforts to walk. Initially, the problem can last just a few seconds and occur very infrequently. As the problem progresses, however, freezing can last many seconds, occurring frequently throughout the day. This can lead to a very frustrating situation that may also be dangerous. People with freezing of gait have an increased risk of falls and reduced health-related quality of life.
The behavioral manifestation of freezing of gait is a problem with walking, i.e., it is a “motor” symptom. However, there is also evidence that deficits in specific aspects of cognitive function (i.e., executive function) may also contribute to freezing of gait. The goals of the present work were to use non-invasive brain stimulation to better understand if these cognitive deficits are indeed in the causal chain and if non-invasive brain stimulation that simultaneously targets both motor and cognitive brain areas that are believed to involved with freezing have a better impact on freezing and related symptoms than stimulation that targets only motor brain areas or sham stimulation.
MedicalResearch.com: What are the main findings?
Response: We evaluated the effects of 20 minutes of multi-target transcranial direct current stimulation (tDCS) in twenty Parkinson’s disease patients who often experience freezing of gait. The subjects received transcranial direct current stimulation on three separate visits. Transcranial direct current stimulation targeted the primary motor cortex and left dorsolateral prefrontal cortex simultaneously, primary motor cortex only, or underwent “sham” / placebo stimulation.
The participants completed a freezing of gait-provoking test, a dynamic mobility test (the Timed Up and Go test), and a cognitive test for processing speed, selective attention and inhibition control (Stroop test) before and after each transcranial direct current stimulation session.
The main finding is that freezing of gait was reduced, i.e., improved, after simultaneous stimulation of the primary motor cortex and left dorsolateral prefrontal cortex, but not after primary motor cortex only or sham stimulation. After 20 minutes of multi-site stimulation, the patients’ freezing of gait was reduced and mobility and cognition improved, more than that seen after stimulation of primary motor cortex only or through sham simulation.
In other words, the results of the study reveal that transcranial direct current stimulation designed to simultaneously target motor and cognitive regions apparently induces immediate aftereffects in the brain that translate into reduced freezing of gait and improvements in executive function and mobility, two functions previously related to freezing of gait.
MedicalResearch.com: What should readers take away from your report?
Response: The report supports the idea that both motor and cognitive deficits contribute to freezing of gait among people with Parkinson’s disease. Further, when thinking about treatment, the results demonstrate that a more positive effect is obtained when both motor and cognitive areas are targeted. More generally, the findings of this study indicate that even among patients with relatively advanced Parkinson’s disease and freezing of gait, it is apparently possible to improve brain function, in this case via non-invasive brain stimulation, at least in the short-term, and this has positive, functional consequences.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: In the present study, the acute and immediate effects of 20 minutes of brain stimulation were examined. To better understand underlying mechanisms, brain plasticity, and the potential to use this type of non-invasive approach as a possible adjunct clinical therapy, questions about longer-term effects need be investigated. A larger-scale, randomized controlled trial is currently being conducted to address questions about retention and long-term effects.
Moria Dagan, Talia Herman, Rachel Harrison, Junhong Zhou, Nir Giladi, Giulio Ruffini, Brad Manor, Jeffrey M. Hausdorff. Multitarget transcranial direct current stimulation for freezing of gait in Parkinson’s disease. Movement Disorders, 2018; DOI: 10.1002/mds.27300
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