One of the most distressing features of a panic attack is the way they affect people out of the blue - or do they? Alicia E. Meuret, assistant professor of psychology at Southern Methodist University and colleagues, have discovered that a number of subtle but important changes occur in the body up to an hour before the onset of an attack. The problem for people prone to panic is they remain completely unaware of what is happening.

During the study, volunteers who experience panic attacks...