The promises and perils of personalized medicine and antidepressants

While there’s a lot of talk about how personalized medicine and biomarkers could improve treatment for people with a range of diseases, the technology isn’t yet ready for prime time, Dr. Raymond Lam, a researcher and professor of psychiatry at the University of British Columbia, told last month’s Mental Health Summit in Vancouver.

Diagnosis of depression involves the presence of at least five symptoms, such as problems with sleep, appetite, energy level, memory and concentration; and feelings of guilt, hopelessness and suicidal thoughts. A sad mood or loss of interest and enjoyment must also be present. But despite the availability of good treatments, finding the right one for a particular patient to treat the 227 possible combinations of symptoms of depression remains a challenge, said Lam.

“We now have the promise of biomarkers to help us better deliver personalized care,” he told the audience.

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Biomarkers are biological characteristics that indicate normal versus abnormal processes, identify subgroups within a disease and predict response to a treatment. Despite all of the research underway on biomarkers with the hope of being able to choose the right treatment, speed up time to recovery, improve understanding of disease processes and point to new interventions, the dream isn’t yet a reality.

“To be clinically useful, a biomarker has to be useful at the level of the individual and unfortunately, we don’t have a biomarker that can tell us that,” said Lam.

Pharmacogenetic testing seems closest to being clinically useful for identifying biomarkers. By determining how people metabolize a drug in their system, the results may indicate a high or low potential for side-effects and the need for a particular dosage.

While the information may seem useful for choosing an appropriate drug or dosage, several factors complicate the issue. Lam also stressed there’s no good evidence that routine testing shows better outcomes in terms of response or side-effects. “In particular, there haven’t been studies to show whether it is cost-effective for us to test everyone before treating them with an antidepressant.”

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Lam concluded his presentation by explaining how a major research project, the Canadian Biomarker Integration Network in Depression, is currently looking for biomarkers for treatment response to antidepressants, psychotherapy, neurostimulation and other interventions. “We think it won’t be a single test of biomarkers but a combination of biomarkers that will be important, perhaps a combination of imaging and molecular markers,” said Lam. “The first phase of the study is just finished, and we hope next year to give a better idea of which biomarkers are clinically useful.”