Dopamine levels clue to schizophrenia

People who may be at risk of schizophrenia show increased levels of the brain chemical messenger dopamine, according to a new study published on line in the journal the Archives of General Psychiatry.

Dr Oliver Howes and colleagues at the Medical Research Council Clinical Sciences Centre, Hammersmith Hospital and Institute of Psychiatry, King’s College London used a brain scanning technique to measure levels of dopamine in people attending the Outreach and Support in South London (OASIS) clinic.  This specialist clinic is for people who show possible early signs of schizophrenia.

The researchers compared the brain dopamine levels in those patients attending the OASIS clinic to levels in people already diagnosed with schizophrenia, and volunteers free of such problems. Dopamine levels were elevated in the people who may be at risk of schizophrenia, to a degree approaching that seen in the patients with schizophrenia. The team also found that higher levels of dopamine were linked to more severe symptoms and to worse performance on thinking tests.

Dr Howes, Senior Clinical Lecturer at the MRC-Clinical Sciences Centre said: “Schizophrenia is one of the top ten health problems in young adults worldwide. Current treatments are helpful but we desperately need better ones.”

“The holy grail of research is to find a way of preventing this devastating illness before it starts. Our finding that dopamine levels are high in people showing very early signs of developing schizophrenia gives an important clue as to what is causing schizophrenia and other psychotic illnesses.”

“If the results are confirmed, future treatments could target this part of the brain’s dopamine system to prevent the full development of the illness. As roughly 1 in 10 people with schizophrenia die from suicide, predominantly in the first few years after the illness starts, a treatment that prevents the full illness could save many lives as well as alleviating suffering. The scans, in conjunction with previous work by us and others, also indicated that the problem is specific to a particular part of the dopamine system. This suggests that all current drugs are acting in the wrong place to address the primary problem – designing drugs to reverse the primary problem could offer the hope of better treatments for schizophrenia."

(Source: Medical Research Council UK: Archives of General Psychiatry: February 2009)