Researchers at Loyola University Medical Center say they may have found a way to predict whether an antidepressant will work on a depressed patient.
A recent Loyola study found that the blood test for a protein called vascular endothelial growth factor (VEGF) could help predict successful treatment. The researchers found that among depressed patients who had higher than normal levels of VEGF, more than 85 percent experienced partial or complete relief after taking escitalopram (Lexapro).
Fewer than 10 percent of depressed patients who had low levels of VEGF responded to the drug.
“This would be the first time we would have a predictor for how well a patient would respond to an antidepressant,” said Angelos Halaris, M.D., Ph.D., first author of the study.
About 60 percent of depressed patients do not respond fully to the first prescribed medication, researchers note. This means doctors must prescribe several different medications before finding one that works. “It would greatly benefit our patients if we could predict ahead of time whether a given medication would be effective for a certain patient,” Halaris said.
The Loyola study involved 35 patients who took escitalopram for depression. Escitalopram belongs to a class of antidepressants called selective serotonin reuptake inhibitors (SSRIs). Other common SSRIs are Prozac, Paxil and Zoloft.
Scientists aren’t certain why SSRIs work in some patients but not in others, the researcher notes. One possible mechanism is that SSRIs help restore a chemical balance in the brain. Some scientists have proposed a second possible mechanism, called neurogenesis, which means that SSRIs help to regenerate brain cells in specific parts of the brain that have atrophied in depressed patients.
The Loyola study supports the neurogenesis theory. It appears that escitalopram jump-starts brain cells that have become inactive. This regeneration is fueled by VEGF, which stimulates the growth of blood vessels and works in other ways to keep brain cells healthy and active.
It appears that in patients with higher levels of VEGF, there was more regeneration, helping to reduce depression, the researchers found. In patients with lower VEGF levels, there was less regeneration of brain cells and, therefore, less relief from depression.
If the finding is confirmed by further studies, it could lead to a blood test that would help physicians tailor treatment, the researchers note. If a patient has low levels of VEGF, the physician might skip SSRIs and try alternative classes of antidepressants, such as bupropion, or alternative therapies, such as psychotherapy or Transcranial Magnetic Stimulation (TMS), researchers explain.
Today, a VEGF blood test would be very expensive, but the cost likely would come down significantly if a VEGF test were to become widely used, Halaris said.
Source: Loyola University Medical Center