It was a Friday afternoon, and Dr Ed White was working at his desk in his home office. “I was suddenly hit by a rush of anxiety,” says the 56-year old IT executive. “It came from nowhere: my heart was pounding, I had a rush of adrenalin, and became extremely agitated.” White, who lives in Wiltshire with his wife and two teenage sons, has no memory how this particular episode two years ago ended. But, from bitter experience, he knew the cause: it was withdrawal from his antidepressant medication….