Schizophrenia may be an array of different disorders rather than one single disease, doctors believe. Research carried out in the United States suggests there could be at least three different types.

Doctors suggested the finding could help to dramatically improve their understanding of schizophrenia and help in the development of new drugs to fight the disease.

Dr Bruce Turetsky and colleagues at the University of Pennsylvania compared symptoms and brain patterns in 116 people with the disease and 129 healthy people. Both groups were assessed using the California Verbal Learning Test which examines learning and memory skills and their recall ability. They also underwent scans to examine the physical make-up and chemistry of their brain.

The tests revealed three distinct types of schizophrenia.

In the first group, parts of the brain called temporal lobes were smaller. They also transmitted fewer chemicals in these areas, which are linked to language and memory. They had problems paying attention, organising their thoughts and expressing ideas in a logical and coherent way.

They were mostly young males who had been diagnosed with schizophrenia at an early age. It affected almost one in five of those with the disease involved in the study.

In the second group, doctors discovered changes in the frontal-striatal region of the brain. They had less grey matter in the frontal lobes and had enlarged ventricles. This area affects cognition and motor function. Their temporal lobes were normal.

Almost one in three of those with the disease who were involved in the study fitted into this category.

More than half of the remaining patients had mild memory problems. Damage to their temporal lobes or frontal lobes was not as great as those included in the other two groups.

The doctors suggested that their findings may explain why a broad range of symptoms can be diagnosed as schizophrenia.

They added that their study may also indicate why scientists have found it difficult to identify the causes of the disease - particularly if they believe it is just one disease.

Dr Turetsky said: "One of the reasons we haven't been successful in identifying 'the cause' of schizophrenia may be because we are studying mixed groups of individuals who don't really have the same thing wrong with them."

He added: "Our results indicate that there are different neurobiological profiles associated with different presentations of schizophrenia. We may be dealing with more than one disease."

The researchers are now planning to expand their study to find out if differences in the brains of patients remain the same throughout their lives.

The study is published in the journal Neuropsychology which is published by the American Psychological Association.

For more information see: http://www.apa.org/releases/schizophrenia.html