Depression affects an estimated 121 million people worldwide. A person is described as being clinically depressed when his sadness
stretches for weeks, even months, and affects his daily activities. To many
sufferers life comes to a stand- still.
An American survey has revealed that more than 16 percent of Americans will experience major depressive disorders during their lifetime.
There are several stigmas linked to depression, but studies have revealed that it is a medical illness just like diabetes or a heart condition. This condition does not merely affect the mind but makes an impact on the entire being of a person.
The individualized treatment approach has revolutionalized treatment for depression by optimizing the effectiveness of the treatment and by reducing side effects.
Genetic factors play an important role in a person's response to drugs and in the side effects that he suffers; however one study has found that environmental factors have a greater role to play!
It has been understood that there is a complicated nexus between genes, environment and drug response. It is hoped that studies in genetic variability would help to understand a person's response to medications for mental illness, particularly in those who are drug-resistant.
The term "pharmacogenetics" has been used to describe the mechanism by which gene variation influences drug response and the rate of side effects.
Detecting specific "candidate" genes would allow the therapists to predict the manner in which an individual metabolizes a medicine. This in turn would enable doctors to choose the correct therapy that is most suitable for that patient, thereby, helping to reduce side effects.
STAR*D, is the largest prospective study of unipolar depression which enhanced pharmacogenetic knowledge about antidepressant response and tolerability. Various markers were explored in this study that could influence treatment modality of this illness and it was found that a combination of genes, rather than a single gene, can act as markers, or predictors, of response to anti-depressants.
In January 2005, the FDA approved the Roche AmpliChip CYP450 genotyping test for variants in the gene CYP2D6 and CYP2C19, using the patients DNA derived from buccal or blood samples. The test helps therapists to determine appropriate treatment plans, including dosing, for medications metabolized by CYP2D6 or CYP2C19. It analyzes the patient's DNA to predict if he or she -
· has more difficulty reaching therapeutic concentrations;
· responds normal medicine metabolizing capacity
· experiences more adverse effects;
· is a poor metabolizer and at higher risk for overdose.
Although genetic testing may influence treatment choices, current data is not adequate enough to be conclusive. However, with further research the dream of personalized therapy is soon likely to become a reality!
Reference: Pharmacogenetics and Depression: Realized Dream or Great Expectation?; Jolene et al; US Pharm. 2011;36(11):72-76.