An Overview of Pharmacogenomic Testing for Psychiatric Disorders

Pharmacogenomic testing is a precision medicine technology that examines genetic variation in medication metabolism. Selected for inclusion in CADTH’s 2023 Watch List, pharmacogenomic testing has the potential to significantly influence the landscape of health care in Canada over the next 5 years. By analyzing an individual’s unique genetic profile, this testing aims to guide personalized treatment strategies that improve therapeutic outcomes, optimize the medication selection process, and enhance patient experiences. The integration of pharmacogenomic testing into clinical practice may pave the way for a more efficient and effective delivery of mental health care.

Pharmacogenomic tests for psychiatric disorders that are available in Canada include direct-to-consumer tests  which are paid out of pocket  and tests that are offered as a laboratory service (which may or may not be paid out of pocket). These tests are quite different from each other, including the types and number of genes examined, cost of testing, and methods used for sample collection and analysis.

Despite being available for approximately 20 years and that numerous guideline-developing groups and regulators have issued recommendations about the types of pharmacogenomic information that should be used to guide prescribing decisions, pharmacogenomic testing has yet to be integrated into most psychiatric care practices in Canada and worldwide. Although some studies suggest pharmacogenomic testing provides benefits over treatment as usual, the evidence is often conflicting and of limited quality. Concerns related to risk of bias, inconsistency across studies, reproducibility, and generalizability do not allow a clear and consistent interpretation of the results.

This Horizon Scan provides an overview of information related to pharmacogenomic testing for psychiatric disorders, a description of some of the published studies, and a summary of some important considerations related to clinician education and training, privacy and confidentiality of health data, health equity, and laboratory capacity should testing become more widely used in Canada.