Genetic testing could be a ‘revolution’ in psychiatric care

Embargoed until 12 July 2012

Patients who experience adverse side-effects from their psychiatric medication could benefit from pioneering genetic research. Dr James Kennedy, of the Centre for Addiction and Mental Health in Toronto, told delegates at the Royal College of Psychiatrists’ International Congress in Liverpool that genetic testing is helping to predict how patients will react to different types of antipsychotics.

Antipsychotic medication is used to treat symptoms of mental disorder such as schizophrenia and bipolar disorder, but can have adverse side-effects. Dr Kennedy said that older antipsychotics (called ‘typical’ antipsychotics’) can cause tardive dyskinesia (trouble with movement) in 25% of patients. The newer ‘atypical’ antipsychotics are as effective as the older ones, but can cause dangerous weight gain in up to 50% of patients.

Speaking at the conference, Dr Kennedy said: “Currently the physician faces a dilemma in writing the prescription. They have to decide, do I take the risk of weight gain or the risk of tardive dyskinesia in this patient? If a genetic test is able to provide information in terms of risk for one of these side-effects, there is an opportunity to reduce suffering in the patient.”

Dr Kennedy and his team have been genetically testing patients in their hospital, and using this genetic information to work out which medication is the best to prescribe, and in what dose. The patient is given a small kit and instructed to swab some of their saliva with a tiny cotton brush. The brush is then placed in an envelope, and the sample is sent by courier to the genetic laboratory. The tests are performed overnight, and thus the delay in starting treatment is minimal. The current set of genes investigated in the lab is typically two or more variants in the liver that influence the level of the psychiatric drug in the bloodstream, as well as three or four genes that affect the receptors in the brain that are the target of the drug’s action.

Dr Kennedy said this approach had also led to success in relation to antidepressants. He gave the example of one patient, with severe obsessive compulsive disorder, who had tried 10 different types of antidepressant medication over a two and a half year period. She did not respond well to any of the medication combinations, experiencing many side-effects including weight gain. Genetic testing helped the psychiatrists work out the best antidepressant medication and dosage for her.

Dr Kennedy said: “If we had known this before, we could have helped get the patient to the right treatment much sooner. Genetic technology is powering ahead – tests can be done overnight, and it is cheap and quick. I can see a future where patients may present doctors with a print out of the genetic results, who could then get the right medication prescribed. This could be a small revolution in psychiatric care.”

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Dr James Kennedy was speaking at The International Congress of the Royal College of Psychiatrists 2012 in Liverpool, 10-13 July.