Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease. It is mostly characterized by the presence of motor difficulties. However, it can also be accompanied by cognitive disorders which have an equally significant impact on the quality of life of patients and which are not relieved by any treatment. Among the functions affected by Parkinson's disease, inhibition is an essential process for adapting our behaviors in daily life. Inhibition allows us to stop an action that is no longer required or appropriate to the situation in which we find ourselves in. For example, it comes into play when we have to stop at a "stop" sign while driving. Recent studies suggest that it could be possible to improve the functioning of these processes by using non-invasive brain stimulation tools. Transcranial alternating current electrical stimulation has thus showed promising results in improving functions such as working memory. This technique is completely painless and non-invasive and consists in applying an electric current of very low intensity (barely perceptible) at the level of the scalp, using electrodes. The investigators are conducting a study to test whether transcranial alternating current electrical stimulation could improve the functioning of the inhibition process which is altered in patients. For this, the investigators will measure this process using a task performed on a computer (the Stop Signal Reaction Time Task), as well as brain activity using a method called "electroencephalography", before and after stimulation. For this study, the investigators will include 50 patients and 40 healthy participants to investigate the effect of the stimulation on inhibition.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
90
interview with a neuropsychologist and carrying out tests measuring overall cognitive abilities, depression, apathy and anxiety (respectively using the MOCA, MADRS, LARS, STAI scales)
Only for patients with Parkinson disease. Evaluation consisting in a disease severity assessment using the Hoehn and Yahr and Schwab and England scales, as a well as a measure of levodopa equivalent daily dose.
The task consists in pressing a left or right button as fast and as accurately as possible according to the direction of an arrow displayed at the center of a screen. On 25 % of the trials, a "stop" signal will occur right after the stimulus, indicating the participant to stop his impending button press. The delay between the presentation of the arrow stimulus and the stop signal will be adjusted to ensure a final 50% accuracy (decreased following an accurate response and increased after an error), which is necessary to comply with the assumptions for a robust calculation of the stop signal reaction time (SSRT).
A high-resolution (256 channels) electroencephalographic recording will be done at rest and during the Stop task, before and after each real or sham stimulation.
Real or sham tACS will be applied with the same equipment (StarStim, Neuroelectrics). The stimulation will consist in applying a current (max 2 mA) at frontal sites (F8 and Cz according to standard EEG position, and defined based on dosimetry analyses on averaged head models) for 12-15 minutes during the task. A 10 s ramp (fade-in/fade-out) will be used to avoid current perception of the stimulation and optimize blinding. Sham stimulation will be done using the same protocol, but with no stimulation in between onset and offset.
CHU de Rennes
Rennes, France
RECRUITINGDifference in cognitive performance measured by the stop signal reaction time (SSRT) compared between real and sham stimulation conditions
Time frame: 5 months
The difference in the dynamic changes in functional networks during the task between real and sham stimulation.
The difference in the dynamic changes in functional networks during the task between real and sham stimulation measured by the averaged lifespan (in ms) if the networks identified with the weighted phase lag index.
Time frame: 5 months
The difference in network parameters derived from graph theory between real and sham stimulation.
The difference in network parameters derived from graph theory between real and sham stimulation. measured by the functions of the brain connectivity toolbox (matlab) : degree distribution, path length, betweenness centrality, clustering coefficient.
Time frame: 5 months
The existence of correlations between the changes in network measures between real and sham stimulation mentioned above and the behavioral differences measured between real and sham stimulation.
Correlations will be calculated in R using the spearman rank correlations between (i) changes in network measures between real and sham stimulation : averaged network lifespan, degree distribution, path length, betweenness centrality, clustering coefficient, and (ii) behavioral differences in SSRT (ms).
Time frame: 5 months
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.