Just one dose of an antidepressant is enough to produce dramatic changes in the brain, according to a new study.
According to researchers, brain scans taken of people before and after one dose of escitalopram, a commonly prescribed serotonin reuptake inhibitor (SSRI), revealed changes within three hours.
“We were not expecting the SSRI to have such a prominent effect on such a short timescale or for the resulting signal to encompass the entire brain,” said Julia Sacher, M.D., Ph.D., of the Max Planck Institute for Human Cognitive and Brain Sciences.
While SSRIs are among the most widely prescribed antidepressants worldwide, it’s still not entirely clear how they work, according to researchers. The drugs are believed to change brain connectivity, but over a period of weeks, not hours, researchers noted.
The new study shows that changes begin to take place right away.
Study participants — medication-free individuals who had never taken antidepressants — let their minds wander for about 15 minutes in a brain scanner that measures the oxygenation of blood flow in the brain.
The researchers analyzed three-dimensional images of each individual’s brain by measuring the number of connections between small blocks known as voxels (comparable to the pixels in an image) and the change in those connections with a single dose of escitalopram, which is sold under the trade name Lexapro.
The whole-brain network analysis shows that one dose of the SSRI reduces the level of intrinsic connectivity in most parts of the brain. However, the researchers observed an increase in connectivity within two brain regions — the cerebellum and thalamus.
The researchers say the new findings represent a first step toward clinical studies in patients suffering from depression. They also plan to compare the functional connectivity signature of brains in recovery and those of patients who fail to respond after weeks of SSRI treatment.
Understanding the differences between the brains of individuals who respond to SSRIs and those who don’t “could help to better predict who will benefit from this kind of antidepressant versus some other form of therapy,” Sacher said.
“The hope that we have is that ultimately our work will help to guide better treatment decisions and tailor individualized therapy for patients suffering from depression.”
The findings were published in the Cell Press journal Current Biology.
Source: Cell Press