Two groups will participate in this trial with a ratio of 1:1, and the following steps will be taken to randomly assign the samples.
The first step is to create a random sequence (Random Sequence Generation):
For this purpose, among the restricted randomization methods, the unequal permuted block balance randomization method will be used, and the size of the blocks will be considered from 2 to 8 variables. Based on the Winpepi software, the list of blocks and their random distribution will be obtained.
A researcher who is not involved in any aspect of the intervention will randomly assign subjects to the intervention (tDCS) and control groups using the above method.
The second step, Allocation concealment:
To hide random allocation, the method of sealed envelopes with random sequence (Sequentially numbered, opaque, sealed envelope (SNOSE)) will be used. In this method, after the random sequence is created using the above method, then based on the research sample size (50 people), an opaque envelope is prepared and each of the random sequences created is recorded on a card and the cards are inside the envelope. Letters are placed in order on the outer surface of the envelopes. Finally, the lids of the envelopes are glued and placed inside a box in the same way. At the time of sampling, based on the order of entry of eligible participants into the study, one of the envelopes will be opened and the assigned group of that participant will be revealed.
The third step is to implement the allocation process:
In this study, the researcher (F-A) created a random sequence and the researcher (N-Sh) examined the participants in terms of the study entry and exit criteria and enrolled them in the study and the expert present at the clinic Assigned to groups. therefore, the person who creates the random sequence (F-A) is not involved in other steps such as registration or allocation of participants, and in the process of randomization, the researcher involved in creating a random program is separate from other researchers to reduce possible bias.
It should be noted that the researcher who checks the entry and exit criteria of the study (N-Sh), also performs the desired intervention, but to blind the study, the desired evaluations and study outcomes by another researcher (A-H) will be done and finally, the researcher (F-A) will analyze the data obtained from the study.
For the participants who are in the control group (Sham), the same electrode assembly method will be used to prevent the participants from knowing and blinding. For this purpose, the device settings will be set in study mode and then a very weak current pulse (110 mA in 15 ms, with a maximum current of 3 ms) will be sent every 55 seconds for 20 minutes. In fact, these parameters provide artificial current stimulation with an ineffective dose.