Researchers have found schizophrenia and manic depression may have a similar genetic cause linked to central nervous system development.
Scientists examined the preserved brains of 15 people who had schizophrenia and 15 who had manic depression, also known as bipolar disorder.
The genetic make-up of the tissue was compared with that from a further 15 brains taken from people who had neither illness.
Certain genes involved in producing the Myelin sheaths which insulate nerve cells were lacking in the brains of both psychosis groups.
Previous research has suggested that abnormalities in the expression of Myelin genes may play a role in schizophrenia.
Researcher Sabine Bahn, from Cambridge University, said: "The high degree of correlation between the expression changes in schizophrenia and bipolar disorder provide compelling evidence for common pathophysiological pathways that may govern the disease phenotypes [observable traits]."
The findings are reported in the latest edition of the Lancetmedical journal.
PA