Can Genes Predict Therapy Outcome?
By Jared DeFife
What if you could predict how well a client would respond to psychotherapy? What if a simple test could tell you whether a patient needed psychodynamic therapy instead of CBT? How much time, effort, and frustration would a glimpse into the future save you, your practice, and your patients? According to new research, genetic tests may hold the key for telling us what treatments work for whom.
Dubbed "therapygenetics," the investigation of genetic predictors of psychotherapy outcome is a brave new world for psychiatric research. Therapygenetics seeks to discover markers in our genetic code that we can use to create a road map for the prevention and treatment of mental illness. To date, scientists interested in mood and anxiety disorders have primarily focused on a specific genetic area known as the serotonin transporter-linked polymorphic region (5-HTTLPR). Serotonin is believed to affect a variety of bodily processes, including how hungry we feel, how well we sleep, and how much we want sex. Additionally, some experts believe that the ways our bodies use serotonin affects how we respond to and learn from emotional situations, making some of us more prone to lasting problems with anxiety and depression.
If our genes provide information about vulnerability to depression and anxiety disorders, can they tell us how someone will respond to treatment for the same problems? To find out, clinical researchers in the United Kingdom and Australia, led by professor Thalia Eley at King's College London, collected genetic samples and treatment-outcome data from 359 children undertaking cognitive-behavioral therapy (CBT) for a primary anxiety disorder. The investigators found that children with one form of the 5-HTTLPR gene variation were 20 percent likelier to remain free of anxiety disorder six months after completing CBT than those with the other gene variation.
The mechanism of how genetic differences translate into differential psychotherapy success is uncertain, but the finding suggests that genetic testing can be used to identify clients who might benefit from a specific treatment on the basis of their genetic profile. This kind of "personalized medicine" could vastly reduce wasteful expenditures on ineffective treatments, but making genetic testing a common practice for people seeking mental health services raises serious potential concerns about privacy intrusions and potential discrimination. Also, even though the genetic tests themselves may be highly reliable, the resulting outcomes are far from conclusive.
A 2008 study of nearly 100 adult bulimic patients receiving multimodal mental health treatment (individual therapy, group therapy, day treatment, and adjunctive medication) found results exactly the opposite of Eley's. The same gene variations that predicted greater improvement in CBT for anxious children predicted less treatment improvement in bulimic adults.
In the future, will psychotherapists consult detailed genetic maps charting our deepest secrets and illuminating our biological fates? If its proponents are correct, the day may come in the not-too-distant future when genetic testing for psychotherapy patients becomes a common medical screening test, like a Pap smear or a blood-cholesterol test.
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