http://www.independent.co.uk/life-style/health-and-families/health-news/the-enemy-within-people-who-hear-voices-in-their-heads-are-being-encouraged-to-talk-back-10001499.html

“The voices became a recurring presence, providing an aggressive, unsettling commentary on her life. Waddingham came to believe that they were filming her around the clock, and became paranoid. When she had a neck ache, she assumed a tracking device had been planted under her skin. At the supermarket, the voices would ask each other questions like “Does she know what she’s buying?” – leading her to reach sinister conclusions. “I worried they might have poisoned the food,” she says. “I’d come back with orange juice, milk, bread and cheese, because it’s all I could work out was safe.””