Finding the right treatment for depression is not easy. Physicians have many medications to choose from, however, they know that only a fraction of patients will respond to any given medication. Thus, they employ a “trial and error” approach where they test a specific medication for a few weeks before moving on to another one. Clinical trials have shown that as many as 70% of patients do not respond to their initial prescribed medication. While the trial and error approach does ultimately treat depression in many cases, the delays are a serious issue. Delays in treatment for depression are believed to lead to nonadherence in an estimated 30-60% of patients. Furthermore, adverse drug reactions (side effects) are the leading cause of death in the U.S. and those linked to the use of antidepressants may lead to psychiatric imbalance, leading to increased risk of suicide, anxiety and manic behaviors. Other common side effects of treatment for depression include dry mouth, constipation, blurred vision, nausea, tremor, insomnia and cardiac disturbance. These adverse reactions stem from the fact that different individuals respond differently to medications and much of these differences can be attributed to our unique genetic background.
How Genetic Testing can improve the treatment for depression
Advances in genetic technologies have tremendous potential to improve the treatment for depression and other mental disorders. Genetic testing prior to taking medications can help to improve accuracy of prescription by determining whether an individual will metabolize a specific medication, as well as guide the starting dosage. This significantly reduces any trial and error time and improves treatment outcomes. Genetic testing also improves drug safety and reduces the risk of adverse drug reactions since a patient is not exposed to unnecessary medications at potentially harmful doses.
Genetic Testing in Clinics
With the cost of genetic testing rapidly falling, its application in a clinical setting is becoming increasingly popular. The Clinical Pharmacogenetics Implementation Consortium (CPIC) provides guidelines for the implementation of pharmacogenetics in clinical settings and has made recommendations on genetic testing for multiple disorders. Denmark is leading the way in the area of pharmacogenetics and mental health disorders, including treatment for depression. Psychiatric hospitals in Denmark routinely test for changes in the CYP2D6 gene, which is a key determinant of response to many antidepressants. A Danish study also noted that hospitals that employ pharmacogenetic testing reported a significantly lower consumption of primary care services.
In North America, the benefits of pharmacogenetic testing are being recognized and its application is gaining steam. In the US, many insurance providers cover the cost of pharmacogenetic testing for many classes of medications and the FDA recommends genetic testing for over 60 different medications. However, payer reimbursement policies exert a great influence on the adoption of pharmacogenetic tests into clinical practice.
Where to find genetic testing for treatment for depression in Canada
Canada lags behind the US in the utilization of pharmacogenetic testing largely because insurance companies do not yet cover these tests, but increasing public awareness and pressure are likely to change this. Those individuals that recognize the benefits of genetic testing are turning to companies that offer direct-to-consumer testing. Geneyouin, a genetic testing and consulting company, is the only Canadian provider of direct-to-consumer pharmacogenetic testing.
1. Herbild, L., et al., Do guidelines recommending pharmacogenetic testing of psychiatric patients affect treatment costs and the use of healthcare services? Scand J Public Health, 2011. 39(2): p. 147-55.
2. Herbild, L., M. Bech, and D. Gyrd-Hansen, Estimating the Danish populations’ preferences for pharmacogenetic testing using a discrete choice experiment. The case of treating depression. Value Health, 2009. 12(4): p. 560-7.
3. Ventola, C.L., Pharmacogenomics in clinical practice: reality and expectations. P T, 2011. 36(7): p. 412-50.
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Learn more about role of pharmacogenetics in mental health here