The study will involve four research visits in total, three of these will take place at the Warneford Hopsital and one will take place at the John Radcliffe Hospital. These will be spaced over 2-3 weeks. The stages will be:
- Information call (up to 30 minutes): a researcher will contact you by telephone to tell you more about the study, answer any questions you might have and, and go through a set of initial screening questions to check if you may be suitable to take part
- Screening call (up to 60 minutes): a researcher will go through the participant information sheet with you. If you are happy with the study details, you will be asked to complete and sign an informed consent form indicating your voluntary participation. The team will then ask you some detailed questions about your health, any medication you are taking, your mental health, and some questions to make sure that it would be safe for you to go in the MRI scanner.
- Screening visit (30-60 minutes): you will be asked to provide blood and urine samples, the team will measure your height and weight and take your blood pressure. Your heart function will be assessed using a test called an Electrocardiogram (ECG). You will also receive a physical exam, that will be performed by trained medical personnel.
- Online task (30-60 minutes): two days before the following visit you will complete an online task which must be completed on the two consecutive days prior to the infusion visit (e.g. if your visit is Monday then the task must be completed on Saturday and Sunday). The task involves choosing between two abstract shapes in a computer game in which you can win money in line with how well you do the task.
- Infusion visit (up to 5 hours): before the infusion, you will be asked to complete a computer task. You will also be asked to complete questionnaires and give a urine and blood sample. You will then be randomly assigned to receive an infusion of either ketamine or saline. The infusion will be administered intravenously - during the infusion you will be lying on a bed and medical personnel will be present in the clinic at all times. After the infusion you will be asked to complete a range of questionnaires and computerised tasks. Once the qualified personnel is satisfied that you are safe to leave, the team will book a taxi to take you home.
- Research visit 1 (up to 4 hours): the next day you will complete a computer task. After this you will be taken to the John Radcliffe Hospital for an MRI brain scan. During the scan you will be asked to lie still on a table inside a 7 Tesla MRI scanner. The scan will last up to 120 minutes. During the scan, we will ask you to complete some computer tasks. In one of these tasks you will receive electrical pain delivered to the back of your left hand. The painful stimuli will be delivered for a very brief duration (less than 1 second) and by a piece of research equipment that produces a low-level electrical output that can induce a moderate and brief pain sensation. The intensity of this pain sensation will be calibrated before the scanning session based on your personal pain sensitivity threshold to be acceptable to you.
- Research visit 2 (up to 2.5 hours): During this visit you will be asked to complete a number of questionnaires and cognitive tasks. One of these tasks will probe how you perform under challenging situations. During this task we will measure your heart rate, and take saliva samples to allow us to measure levels of cortisol and alpha amylase.