Robert J Sawyer 
Triggers 

The president of the United States is shot in the head by a would-be assassin. Rushed to hospital and barely saved from death, he discovers that he has new memories – memories that are not his own. A scientific experiment has gone awry, and a small group of people now remember each other’s lives. And when one of those people’s lives involved access to the most secret and dangerous information in the world, everything will change.