New DNA test could end 'trial and error' of antidepressant treatments

CTV National News: DNA and depression Avis Favaro reports on a new test that will give doctors insight into whether a prescription will work for a patient.

The future of psychiatric medicine may lie in our DNA.

A new genetic profile test is bringing personalized medicine into the realm of psychology by determining how individual patients are predisposed to respond to more than 30 different drugs.

Some in the medical community think the test could change the way doctors help patients with depression, who often go through expensive and frustrating periods of “trial and error” with antidepressants before they find a drug that works.

“Everyone is going to want this test as people become more aware of the power of DNA,” said Dr. James Kennedy of the molecular brain science department at Toronto’s CAMH, where he is part of an ongoing study called “IMPACT: Individualized Medicine: Pharmacogenetic Assessment & Clinical Treatment.” He said widespread use of the test would reduce health care cost due to shortened treatment and avoidance of side effects and hospitalizations.

The genetic testing tool is called GeneSight and is offered by Assurex Health, a subsidiary of Myriad Genetics Inc. The test — which is not covered by provincial health plans and costs $1,500 if not administered in a clinical trial — analyzes cells taken from a patient’s saliva or cheek swab to determine how a patient’s body metabolizes drugs and predict how they will react to 33 different medications. The results are categorized into a colour-coded list: green means go, or “use as directed,” yellow means “use with caution,” and red means avoid, or “use with increased caution and with more frequent monitoring.”

Kennedy has tried the method on more than 11,000 patients, he said. The results have been encouraging and they plan to release the data in 2019. “It gets the patient better faster — in four or five weeks — without having to go through all this frustrating trial and error,” he said.

For Larry Meikle of Kanata, Ont., the test was a godsend. He had temporarily stopped taking his old medication for anxiety and depression and when he returned to them, they simply stopped working. His distressing anxiety symptoms returned. He was prescribed a new medication but felt it wasn’t working well enough.

But with Meikle’s genetic test results, his doctor doubled the dose of an existing medication. Now, Meikle feels a greater sense of calm. He even went back to school.

“That’s been wonderful and I never could have done that feeling the anxiety that I felt before,” he told CTV.

Meikle isn’t the only success story. Results of a recent study presented at the American Psychiatric Association’s annual meeting in New York City last month showed that patients who took drugs selected on biological evidence were 33 per cent more likely to respond to treatment quickly. In the 24-week study, researchers examined the treatment response of more than 1,100 patients, one group whose DNA was tested using GeneSight, and another group whose primary care physicians prescribed medication as normal, without the new tool. At week eight, people in the GeneSight group were 50 per cent more likely to achieve remission and 30 per cent more likely to respond to treatment.

A review of the test by Health Quality Ontario in April of last year found that patients who had the test experienced improved moods and responded better to treatment, but said the scientific evidence was not strong enough to recommend the province fund the test.

With files from CTV’s medical affairs specialist Avis Favaro and producer Elizabeth St. Philip