The only thing I can currently measure in the app is the intensity of an emotional experience - before the process and after the process. I'm still compiling the stats, but I think the average reduction in intensity of the experience of e.g. apathy is about 40%.

I really like the idea of incorporating a standard depression symptoms test into the app and then taking another test at a later stage to see the longer term change. It still won't be conclusive proof, but it would help.