I'm sorry but all I can offer is my experience with them. We may not even be thinking of the same thing. A doctor long ago attributed them to "a touch" of OCD. I'm not sure if there is any way to actually prevent them. I don't know if the meds I take help but I don't have any reason to think they have an effect one way or the other. I know how unsettling (nice word huh?) they can be. I can recall a couple in particular. Once I was in a reception room and it was very nice... the was a shelf with nice little figurines and such. I had a sudden urge or picture in my mind of just sweeping my hand across them and destroying them. Another one was talking to someone and having this thought of punching them in the face. There was no anger, no provocation, and it came during a normal, pleasant conversation. Just out of nowhere having a thought of punching someone for no reason was very disturbing. I'm not a violent or angry person. I thought I must be going insane. There were other types of intrusive or what I think of as unwanted and uncharacteristic thoughts. I'd have to really reach to recall any specifics. I was really stressed out and anxiety was at about 10 when most of it happened. Does any of that sound similar?