The first study will check whether a single dose of the medicine can have an effect on – shift – serotonin brain activity, and is therefore called a ‘shiftability’ trial. A single dose of the medication will be given to participants, on one occasion, while they complete tasks of emotion and sensory processing, sustained attention and ability to stop a repetitive behaviour in an fMRI scanner. There will also be a ‘resting’ MRI scan.  Other sensory tests will be conducted out of the scanner. On another occasion, a harmless sugar pill called a placebo will be given to participants and they will perform the same scanning and testing session. The responses of autistic and non-autistic adults and the effects of the treatment and placebo will be compared.
Assuming that they pass this first study, the most successful of either this GABA medicine or the serotonin-based medicine will go on to be AIMS-2-TRIALS’ ‘fast-fail’, so called because it aims to be a relatively fast way to test whether a medicine that has already been approved is useful in another way in autistic people. This will test a longer term course of the medication in a larger group of autistic and non-autistic adults. If it is not successful, researchers know that it has ‘failed’ and do not proceed to a full clinical trial. For the fast-fail trial, participants will be allocated randomly into either the medication or control group – a group that is given a placebo, as above – and will all take part in a number of tests over the time that they are taking it. These tests will be similar to those of the first study. Side effects will be monitored and participants will be able to leave the study at any time, should they wish.