Multiple Sclerosis
Conditions
Brief summary
Multiple sclerosis (MS) is a chronic inflammatory disease with around 200.000 patients in Germany. Besides physical symptoms, cognitive resources degrade over the years. Transcranial direct current stimulation (tDCS) is an established procedure to modulate cortical excitability in motor and cognitive functions. Therefore, tDCS may improve cognitive functions in patients with MS. Patients will work on a modified version of the symbol digits modalities test in two experimental sessions. During the task, they will receive either active stimulation or sham stimulation in a crossover design. Active stimulation is divided in anodal and cathodal stimulation. Anodal stimulation should facilitate cognitive processing; cathodal stimulation, on the other hand, should hinder cognitive processing.
Detailed description
Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease characterized by a multitude of symptoms, which greatly reduce the quality of life of patients. In addition to sensory and visual sensory disorders, movement disorders, paresis, fatigue and other physical symptoms, 65-95% of patients with MS also suffer from cognitive impairments. These cognitive impairments develop in the later course of the disease and express themselves in slower processing speed, delays in learning and memory performance, and executive dysfunction. In recent years, non-pharmacological approaches aimed at improving cognitive performance in MS have increasingly come into focus, including the transcranial direct current stimulation (tDCS). TDCS has only been investigated in a few studies that had the aim to improve cognitive performance in MS. Further, it has only been carried out in combination with cognitive training paradigms and repeated stimulation sessions. Mattioli and colleagues (2016) could e.g. show that after 10 sessions of cognitive training with tDCS stimulation of the dorsolateral prefrontal cortex, there was greater improvement in symbol-digit modalities test (SDMT) in the experimental group than in the control group. Similarly, Charvet and colleagues (2018) showed that after 10 sessions of cognitive training with simultaneous tDCS stimulation of the dorsolateral prefrontal cortex, the experimental group showed a significant improvement in the domains of attention and response variability compared to the control group. These studies therefore reflect an interaction between cognitive training and tDCS, and do not allow any conclusions to be drawn about the effect of tDCS on specific processes. It is not yet known whether tDCS alone can positively influence specific cognitive functional impairments. Therefore, the present study wants to investigate whether acute application of tDCS can improve specific cognitive functions. An adapted version of the clinically SDMT was conducted, as this test is one of the most widely used tests to describe cognitive impairments in MS. Based on a meta-analysis by Silva and colleagues (2018), that shows which brain areas are related to the implementation of the SDMT, the parietal cortex (BA7) is stimulated bilaterally with either excitatory (anodal) or inhibitory (cathodal) tDCS.
Interventions
DEVICEActive transcranial direct current stimulation
A high-definition tDCS set-up will be used with a battery-driven stimulator (Starstim 8, Neuroelectrics). Active stimulation will be conducted with 1.5 milliampere (mA) with two electrodes using three reference electrodes for each active one for 20 minutes.
DEVICESham transcranial direct current stimulation
A high-definition tDCS set-up will be used with a battery-driven stimulator (Starstim 8, Neuroelectrics). Sham stimulation will have a 40 seconds ramp-up and down. No stimulation will be applied after this 40 seconds.
Sponsors
University Medicine Greifswald
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Masking description
Participants and investigators are blinded according to the sham / active stimulation.
Intervention model description
Randomized, balanced crossover design.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* diagnosis of multiple sclerosis. * no acute inflammation during the last 3 months before the experimental intervention. * no cortisol treatment during the last 3 months before the experimental intervention. * stable medication during the experimental intervention. * unrestrained or corrected visual ability. * ability to read and write short german sentences. * adequate motor ability to give responses on a keyboard. * German as main language.
Exclusion criteria
* major depressive symptoms or any further neurological and/or psychiatric disease at experimental intervention. * standard tDCS
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Reaction Times in symbol-digit modalities test. | Assessed at two timepoints (1x during active (anodal/cathodal) tDCS intervention at Day 1 or 7 (depends on randomization), 1x during sham tDCS intervention at Day 1 or 7 (depends on randomization)) | Reaction times in milliseconds for the performance of the symbol-digit modalities test. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Hit Rate in symbol-digit modalities test. | Assessed at two timepoints (1x during active (anodal/cathodal) tDCS intervention at Day 1 or 7 (depends on randomization), 1x during sham tDCS intervention at Day 1 or 7 (depends on randomization)) | Hit rate in percentage of correct responses in the symbol-digit modalities test. |
| Baseline performance in symbol-digit modalities test. | Assessment at baseline (Day 0, before stimulation). | Baseline performance of paper-pencil version of the symbol-digit modalities test as a predictor for the stimulation effect. |
Countries
Germany
Outcome results
None listed