Once I watched a movie, not sure but probably in past 7 years, it was on national TV, so certainly it was not a new movie at that time. There were 2 brothers. One of them was super intelligent. He saw that in certain area in Texas, people are less violent. He noticed that it was because of the water of that area and he decided to mix it in clouds so that it could affects everyone. Every one in the world was less violent thereafter. In a scene, it showed the war between Israel and Palestine was over, they shook hands etc. However, at the end, people were losing their intelligence and they were not even able to move their body. It ended like this. Main character recorded a video log of these events. Anyone recognize it?
This is a TV version of Stephen King's short story The End of The Whole Mess from his collection Nightmares and Dreamscapes.
The TV version you saw sounds like it was a TNT show from 2006 (the details are in the wiki article).