>they screened 1000 patients to come up with the study population of 59
Note that while not ideal this is completely normal for any early stage drug trial. Most drugs get licenced based on data in which the trials would have excluded 90%+ of the typical clinical population. This is certainly true in depression where most drug trials will exclude patients with comorbid MH conditions, and often exclude them for "too many previous episodes". But it's also true in physical health (e.g. asthma).
I'm sure it's even harder when recruiting for an RCT in psychedelics though. A friend was working on clinical applications of MDMA about 15 years ago and a stipulation of the ethics board was that her participants had to have taken MDMA at least 3 times before, but not more than 10 times. Not easy to recruit for that study!
Note that while not ideal this is completely normal for any early stage drug trial. Most drugs get licenced based on data in which the trials would have excluded 90%+ of the typical clinical population. This is certainly true in depression where most drug trials will exclude patients with comorbid MH conditions, and often exclude them for "too many previous episodes". But it's also true in physical health (e.g. asthma).
I'm sure it's even harder when recruiting for an RCT in psychedelics though. A friend was working on clinical applications of MDMA about 15 years ago and a stipulation of the ethics board was that her participants had to have taken MDMA at least 3 times before, but not more than 10 times. Not easy to recruit for that study!