A brain scan may be able to tell how severe a psychotic patient's illness will become in the future, according to a new study published in the journal Psychological Medicine.

"This is the first step toward being able to use brain imaging to provide tangible benefit to patients affected by psychosis," said one of the study's leaders, Paola Dazzan of King's College in London.

It would stop the practice of prescribing long courses of antipsychotic drugs to people with very mild forms of psychosis, she said. Psychosis, the loss of contact with reality, is commonly seen as a component of schizophrenia and bipolar disorder. But psychotic symptoms can also occur in patients with Parkinson's disease or with alcohol or drug abuse.

Currently, psychiatrists have no good way to tell whether a person who has had one psychotic episode will have more.

Researchers took MRI (magnetic resonance imaging) brain scans of 100 patients after their first psychotic episode, and 91 non-psychotic people, then followed up with them all six years later. A computer algorithm was developed to distinguish between brains scans of patients based on the
severity of their psychosis.

The algorithm was then used to analyze the scans of patients after a first psychotic episode. In 70 percent of the cases, it was able to detect which patients developed severe psychosis versus those with a more benign, episodic form of the illness.