SAN DIEGO—Is genetic testing in psychiatry a dangerous development or a useful addition to a clinician’s toolkit?
A panel of mental health professionals debated this question before hundreds of people at the American Psychiatric Association’s annual meeting Monday, sharing insights on several potential benefits and pitfalls of the increasingly common practice.
Presenter James L. Kennedy, MD, who has been researching genetic testing for 20 years, believes it can be useful in mental health treatment, but that it is far from imperfect and requires more research. Dr. Kennedy is professor and co-head, Division of Brain and Therapeutics at the University of Toronto in Ontario, Canada.
“These tests are not meant to be the be-all and end-all but they’re just another source of information,” he said.
With the proliferation of direct-to-consumer genetic tests offered by companies such as 23andMe and Ancestry.com, patients have the ability to independently order their own tests and get information about their DNA. But that autonomy has downsides, Dr. Kennedy said, as the information can easily be misinterpreted.
“The best thing is to have a physician or someone in the know who can interpret and caution you about overinterpreting some of the genetic information that you’re getting,” he said.
Tests for single-gene disorders, such as Huntington’s disease, are simple and highly accurate. But many others, such as tests assessing the risk of prostate cancer, are much more complex and prone to different interpretations, according to Dr. Kennedy.
“These tests are really not ready for prime time,” he said.
In addition, certain test results can have significant emotional effects on patients, Dr. Kennedy said. For example, an easily available test tells patients if they have a gene that gives them a 95% chance of developing Alzheimer’s disease. Learning they have that gene could induce depression in a patient, increase the risk of suicide, and cause worry among family members, Dr. Kennedy said.
One benefit of drug testing, Dr. Kennedy said, is being able to detect possible serious adverse drug reactions and side effects. For example, in Asian people taking the mood stabilizer carbamazepine, tests can show if someone has a genotype which increases the risk of developing the potentially fatal Stevens-Johnson syndrome by more than 30 times.
Genetic testing can also show the speed at which a person metabolizes specific drugs. Clinicians can use this information to switch treatments or lower or increase dosage levels beyond the standard dose, which Dr. Kennedy said is based on a “normal” profile which only 1 of 6 people has.
Having this knowledge has the potential to lower the number of drug trials a patient has to undergo before finding the best treatment for a disorder such as depression, Dr. Kennedy said.
An interactive component of the session provided a look at some of the clinicians’ experiences with genetic testing.
About 42% said they have never used genetic testing for drug choice in their practice. Only 12% said they order it regularly.
One-third of participants said the biggest barrier to using genetic testing for drug choice in their practice is that they don’t believe it is ready for clinical use. Another third said the biggest barrier is that it’s not cost-effective.
Among those who had ordered genetic testing for drug choice, 87% said it was helpful. Of that group, 73% said the results caused them to avoid or prescribe a certain drug.
Nurmi EL, Kennedy JL, McCracken JT, Pato M, Calarge C. Should I Be Using Genetic Testing to Guide Prescribing? Presented at: the American Psychiatric Association Annual Meeting; May 22, 2017; San Diego, CA.