There is overwhelming evidence that physical or sexual abuse in childhood is a key cause of madness - and probably a far more significant factor than genes in most cases.
In a review of 13 studies, the lowest proportion of women with manic depression or schizophrenia who had been physically or sexually abused as children was 51 per cent, the highest 97 per cent.
Just along the spectrum from full madness is personality disorder; 'me, me, me' people with weak identities and a poor grasp of reality. In a separate study, over half the people with this condition were abused as children, too. These facts alone are rarely even discussed by biological psychiatrists, with their strong bias towards genetic explanations.
Childhood sex abuse impacts on the size of bits of the brain. The hippocampal region is important in the regulation of emotion; on average, it's five per cent smaller in women who were abused in childhood than in the unabused. There are similar findings for the amygadla region.
The earlier the sexual abuse occurs, the greater the loss of hippocampal volume, the weaker the woman's sense of self and the greater the number of sub-personalities she develops. Even the form of madness is affected.
Schizophrenics with a history of abuse are more likely to report hallucinations than unabused schizophrenics. The more severe the abuse, the greater the likelihood of seeing or hearing things.
Much-maligned psychoanalyst RD Laing would have predicted exactly these effects. Rather than cope with the fact that the sex is happening, abused children mentally remove themselves from their bodies, perhaps watching from the ceiling. It is only a short step from this to believing you are someone else altogether.
In a famous example of Laing's theory, a mother visited her schizophrenic son in hospital. As the son was about to kiss her on the cheek, his mother froze and turned her head away, so he backed off. She then said, 'Darling, don't you want to show that you're glad to see your mother by giving her a kiss?'
This is known as a 'double-bind', where parents give two contradictory instructions, so that whatever the child does is wrong. Eventually, according to Laing, the only option for the child is to shift to a different order of meaning. Instead of regarding other people's words or gestures as having an overt significance, the child begins to assume that they, and everything else, has a deeper, concealed, more symbolic one.
Incest is the ultimate double-bind. The child may be told that what the parent is doing with them is natural and normal. Yet the child is also told not to reveal what has happened to anyone else and becomes maddened by not knowing what to believe.
It's a disgrace that psychiatrists do virtually no research into further investigating Laing's theories, and continue to largely ignore the overwhelming evidence that abuse is a major cause of madness.