How Genetic Testing Can Determine Which Antidepressant To Use
The one size fits all approach to medicine has always presented problems when it comes to meeting individual needs. The same medication given to different people with similar symptoms can result in any combination of positive, negative or indifferent effects. Slowly but surely however a ray of light on the horizon suggests that bespoke therapies are getting closer.
A procedure already used by several hospitals can help to determine which of a variety of antidepressant or antipsychotic medications are most likely to work or cause side effects. A psychiatric DNA test known as GeneSightRx offers the promise of providing information to doctors in such a way that can help them select or rule out medication. The procedure for the patient is simple. Their DNA is collected via a cheek swab after which genetic testing is undertaken and the results analyzed.
Cincinnati-based AssureRx Health, Inc., who provide the service, say on their website that testing can reveal potential drug interactions or possible side effects. The science behind the testing is a developing area known as pharmacogenetics. Because everyone has a unique gene sequence, these differences can affect whether any given medication will have positive or possibly harmful effects. Establishing a genetic profile can even help to establish how a patient might respond to specific medicines at particular doses.
These are still early days for pharmacogenetics but the field holds up hope for the future. To date, however, very little evidence in the way of patient outcomes is available. A quick review of news reports points to cautious optimism. Peter McGuffin, Professor of Psychiatric Genetics at the Institute of London is quoted in Mark Henderson's report in The Times newspaper. According to McGuffin the science behind the testing is sound but, 'more work is needed to establish whether these tests will provide enough of an advantage over current practice.'
Genetic testing is already proving valuable in other areas of medicine. For example, around 10 per cent of people have a version of the CYP2D6 gene which means they are unable to derive benefit from the painkiller codeine. Knowing this means alternatives can be made available. Various other profiles can be established for cancer treatments, HIV, blood-thinning medication and statins, to name just a handful.
In a very general sense it is estimated that drugs work in just half the people that take them. If personalized medicine can help to improve these odds whilst reducing the risk of side effects or other negative reactions, this would be a significant advance over existing arrangements.