How to Study Placebo Responses in Motion Sickness with a Rotation Chair Paradigm in Healthy Participants

The overall goal of this procedure is to investigate whether a placebo intervention on motion sickness affects subjective outcome measures only, or also affects behavioral and objective measures. This is accomplished by using a balanced placebo design with a rotation chair paradigm in the balanced placebo design, BPD for short. The study group is divided into four subgroups.

Half of the participants receive the real drug and the other half receives a placebo. Half of the participants of each drug group receive the correct information and the other half receives the wrong information about the drug received. With the BPD, we can investigate the effects of a drug compared to a placebo and the effects of expectations by verbal information before and after the rotation procedures.

The participants are asked to rate a list of subjective symptoms that typically occurred during motion sickness, such as vertigo, nausea, or headache. Ideally, the rotation procedure consists of five runs of two minutes each with one minute breaks in between behavioral measures, such as the number of head movements and the total rotation time tolerated are assessed. The gastric myoelectrical activity is objectively recorded with electric gastroscopy, EGG.

After the rotation procedure, the outcome variables are calculated. The EGG data is screened and analyzed to detect shifts from normal gastra to tachy gastra. Prepare the drugs used a table to fill in rotation times and the number of head movements during the runs of the rotation Procedure.

A questionnaire to fill in the symptom ratings of the participant headphones and an eye mask. Prepare the equipment for recording the EGG cutaneous electrodes, the EGG device with fero technology and a stopwatch to assess rotation times. Place three cutaneous electrodes on the skin above the stomach of the participant.

Place the first electrode on the lower third of the midline between the umbilicus and sternum. Place the second electrode in a 45 degree angle, upwards from the first electrode, but under the lowest drip on the left side. Place the third electrode, the reference electrode in a 45 degree angle downwards from the first electrode to the right side.

Connect the electrodes to the EGG device seat the participant in the rotation chair. Start the recording software and store the EGG device in a bag at the backside of the chair. This is important to prevent the cables from getting entangled.

The first baseline assessment is taken before drug intake record at least 15 minutes of EGG previous to any intervention. Instruct the participant not to move, speak, or take deep breaths during this period of time. According to group assignment, the participant takes the pills, drug or placebo without receiving any information about their content.

The second baseline assessment is taken after drug intake record at least 15 minutes of EGG after drug intake. Instruct the participant not to move, speak, or take deep breaths during this period of time. Afterwards, ask the participant for seven symptoms of motion sickness on a scale between zero, no symptom to five severe symptom.

The symptoms are vertigo, headache, nausea, urge to vomit, tiredness, sweating, and stomach awareness immediately before the rotation. Procedure informed the participant about his group assignment according to the balanced placebo design. That is if he received the real drug or the placebo.

Instruct the participant to Move his head up and down when he hears the beep tone from the earphones. Participants should not vomit during the procedure and can skip head movements or tell the experimenter to stop the rotation at any time. If they strongly feel an urge to vomit, the participant will wear an eye mask and earphones and hear a beep every 10 seconds.

Confirm that the participant is ready to begin, then start the rotation procedure. The rotation procedure consists of five, runs each with two minutes of rotation at a constant speed of 120 degrees per second and a one minute break in between the runs. Count the head movements right after The rotation procedure.

Note the rotation time of the run and the number of head movements immediately after. Ask the participant to rate the seven symptoms from zero to five. Note the rating on the questionnaire.

If the participant does not object, repeat the process five times in order to get comparable results. It is important to stick to the same interval of runs and breaks after the last run is finished and the subjective symptoms have been rated. Record another 15 minutes of EGG during which participants should not move.

Speak or take deep breaths. Calculate subjective symptom ratings by adding the scores of each symptom for each of the six time points at baseline. And after each run separately, calculate the maximum symptom rating.

Add up rotation times for the total rotation tolerance in seconds. Add the number of head movements during the rotation procedure for the total Number of head movements. Visually screen the Raw EGG data for artifacts and select at least five minutes of artifact free recording during the recording periods.

As a rule of thumb, artifacts are defined as signals with fast and sudden onset and signals stronger than a thousand microvolt. Because such signals are improbable gastric myoelectrical activities, use a fast four year transformation software to analyze the frequency domain of the EGG signal. Calculate the percentage spectral power of the normal gastra and tachy gastra bands from the total range and compute the EGG ratio.

A shift towards tachy gastra that is a decreasing ratio, has repeatedly been associated with nausea in motion sickness induced by rotation chair or EV action Drum. The conducted study Showed that the information given did not significantly affect the EGG ratio, but results provide hints that the information could have had some effect as the placebo group had the lowest EGG ratio and the ginger group had the highest EDG ratio. Yeah, the main results of this study was in this balanced placebo design that we found no main effect of ginger or placebo, but we found an interaction effect with the gender of the experimenters and the participants.

So in male participants, we found an effect when they got the ginger information, when it was given by the female experimenter. So this was a really interaction effect here. The main advantage of this method is that we have different kind of measures.

We have a very objective measure, the EGG, the electro gastric gastro gram, but also subjective measures. This method thus provides the possibility to assess the main and interactional effects of drug and information, as well as the multivariate assessment of placebo Responses.