It is arguably the one mental health condition that scares people more than any other, and it comes with many names. Years ago people with it were called mad or insane; today it is labeled Schizophrenia or Psychosis - and it’s only now being properly understood.

For decades, psychiatry has treated voices and hallucinations as an enemy, seeing them as something to be suppressed. But new scientific insights into how the brain works are leading to a radical rethink on what such experiences are - and how they should be treated.

Horizon follows three people - David, Rachel and Jacqui - living with voices, hallucinations and paranoia, to explore what causes this kind of phenomena. Providing a rare first-hand insight into these experiences, David, Rachel and Jacqui reveal just what it’s like to live with voices and hallucinations day-to-day.

They examine the impact of social, biological and environmental influences on conditions traditionally associated with insanity, such as schizophrenia and psychosis. They look at how new ways of understanding the brain is leading to a dramatic change in treatments and approaches. And they examine whether targeting the causes of psychosis can lead to recovery.

Above all, they try to uncover why it happened to them - and whether it could happen to you.

EM