One bit of evidence is that in the JHU studies, improvement correlated strongly with whether the person had a "mystical-type" experience. When you go through an

One bit of evidence is that in the JHU studies, improvement correlated strongly with whether the person had a "mystical-type" experience. When you go through an incredibly cathartic experience of remorse and redemption and come out of it a more loving person, it's a good hypothesis that it was the experience that caused the change.