I do not think it is caffeine. Caffeine is often demonized by professionals who should know better. it is actually apparently positively correlated with longevity (caffeine itself and not just the antioxidants in coffee). Also, apparently helps prevent diabetes and Parkinsonism.

I would think that people who should not drink it know that. Say, they get heart palpitations or just a sped up heart rate when they drink it but not otherwise. But if you have been drinking caffeine all along and suddenly are psychotic and scared, why would caffeine be the culprit? It is not that you just started to drink it. I agree with your husband.